Method of Fabricating Nano-structures with Engineered Nano-scale Electrospray Depositions

ABSTRACT

Embodiments relate to a method of manufacturing pinned nano-structures with tailored gradient properties. First and second compositions are provided, Each of the compositions includes a nano-structural material, a plurality of grain growth inhibitor nano-particles, and at least one of a tailoring solute and a plurality of tailoring nano-particles. Deposition layers are formed proximal to a substrate with each of the compositions through electrospray techniques.

BACKGROUND

The present embodiments relate to a method for using electrospraytechniques to directly synthesize nano-structured materials. Morespecifically, the embodiments disclosed herein relate to methods ofimplementing electrospraying techniques to fabricate nano-structureswith tailored, unique properties.

Various techniques for fabricating objects through three-dimensional(3D) printing include additive manufacturing techniques, such as inkjetprinting, fused filament fabrication (FFF), and electron beam additivemanufacturing (EBAM). Many known inkjet devices demonstrate insufficientdeposition control and accuracy through formation of satellite droplets.The FFF process is limited with respect to material selection.Accordingly, these examples of additive manufacturing techniques arebest suited for macroscopic object fabrication due to the scale ofmaterial depositions, such as millimeter (mm) for FFF and EBAMmanufacturing, and microns for inkjet printing.

SUMMARY

A method is provided to form nano-structures with tailored properties onobjects while fabricating the objects.

In one aspect, a method of manufacturing a pinned nano-structure withone or more tailored gradient properties is provided. The methodincludes providing first and second compositions, The first compositionincludes a first nano-structural material and a plurality of first graingrowth inhibitor nano-particles including one or more first grain growthinhibitors. The first composition also includes at least one of a firsttailoring solute and a plurality of first tailoring nano-particles. Thefirst tailoring solute includes one or more first tailoring solutematerials. The first tailoring nano-particles include one or more firsttailoring nano-particle materials. The second composition includes asecond nano-structural material and a plurality of second grain growthinhibitor nano-particles including one or more second grain growthinhibitors. The second composition also includes at least one of asecond tailoring solute and a plurality of second tailoringnano-particles. The second tailoring solute includes one or more secondtailoring solute materials. The second tailoring nano-particles includeone or more second tailoring nano-particle materials. First and seconddeposition layers are formed proximal to a substrate with the first andsecond compositions, respectively.

These and other features and advantages will become apparent from thefollowing detailed description of the presently preferred embodiment(s),taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The drawings referenced herein form a part of the specification.Features shown in the drawings are meant as illustrative of only someembodiments, and not of all embodiments, unless otherwise explicitlyindicated.

FIG. 1 depicts a sectional schematic view of a nano-scale electrospraydeposition system.

FIG. 2 depicts a sectional schematic view of one embodiment of anano-scale electrospray deposition apparatus.

FIG. 3 depicts a sectional schematic view of a magnified portion of anano-scale electrospray deposition apparatus.

FIG. 4 depicts a sectional schematic view of another embodiment of anano-scale electrospray deposition apparatus.

FIG. 5 depicts a sectional schematic view of yet another embodiment of anano-scale electrospray deposition apparatus.

FIG. 6 depicts a sectional schematic view of yet another embodiment of anano-scale electrospray deposition apparatus.

FIG. 7 depicts a sectional schematic view of yet another embodiment of anano-scale electrospray deposition apparatus.

FIG. 8 depicts a schematic view of electrosprayed droplets and bridgingmonolayers formed by grain growth inhibitor nano-particles.

FIG. 9 depicts a schematic view of electrosprayed droplets on asubstrate.

FIG. 10 depicts a schematic view of a gradient alloy with a lineargradient.

FIG. 11 depicts a schematic view of a gradient alloy with a non-lineargradient.

FIG. 12 depicts a schematic view of a linearly-graduated conjoineddeposition layer.

FIG. 13 depicts a schematic view of a non-linearly-graduated conjoineddeposition layer.

FIG. 14 depicts a schematic view of a homogeneous conjoined depositionlayer.

FIG. 15 depicts a sectional schematic view of another embodiment of anano-scale electrospray deposition system.

FIG. 16 depicts a sectional schematic view of yet another embodiment ofa nano-scale electrospray deposition system.

FIG. 17 depicts a flow chart illustrating a process for fabricating anobject with nano-structures thereon.

DETAILED DESCRIPTION

It will be readily understood that the components of the presentembodiments, as generally described and illustrated in the Figuresherein, may be arranged and designed in a wide variety of differentconfigurations. Thus, the following detailed description of theembodiments of the apparatus, system, and method of the presentembodiments, as presented in the Figures, is not intended to limit thescope of the embodiments, as claimed, but is merely representative ofselected embodiments.

Reference throughout this specification to “a select embodiment,” “oneembodiment,” or “an embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“a select embodiment,” “in one embodiment,” or “in an embodiment” invarious places throughout this specification are not necessarilyreferring to the same embodiment.

The illustrated embodiments will be best understood by reference to thedrawings, wherein like parts are designated by like numerals throughout.The following description is intended only by way of example, and simplyillustrates certain selected embodiments of devices, systems, andprocesses that are consistent with the embodiments as claimed herein.

Construction of the Nano-scale Electrospray Deposition System

To provide additional details for an improved understanding of selectedembodiments of the present disclosure, reference is now made to FIG. 1illustrating a sectional schematic view of one embodiment of anano-scale electrospray deposition system (100) that is configured toproduce composite nano-particles, i.e., particulate nano-composites andobjects fabricated from such nano-composites, including graduatednano-structures and gradient alloys. As used herein, the terms“nano-particles” and “nano-composites” indicate particles and compositesthat have a microstructure with a characteristic length scale of whichis on the order of approximately 1 nano-meter (nm) to approximately 10nm.

The nano-scale electrospray deposition system (100) is shown with amaterial supply bin (102). As shown, the material supply bin (102)includes an external casing (104) that defines a cavity (106) therein.The cavity (106) maintains a supply of raw materials (108) therein. Apartial list of raw materials (108) is provided in Table 1 below. In oneembodiment, in addition to the nano-particle addition, the supplied rawmaterials may include a first material, such as aluminum (Al) and asecond material such as titanium (W), although such materials should notbe considered limiting. It is understood that the aluminum (Al) andtitanium (W), or other materials, are used to create the gradientalloys. The apparatus of the bin (102) that allows filling thereof isnot shown. The bin (102) includes an inert gas input and regulatingsystem (110) that includes a gas supply conduit (112), a sealing device(114), and a gas inlet stub (116) that forms a gas inlet conduit (118)and a cavity (120) therein. The gas inlet conduit (118) is in flowcommunication with the gas supply conduit (112). The regulating system(110) also includes a gas pressure regulating device (not shown). Thebin (102) further includes a material outlet conduit (122). In at leastone embodiment, the material supply bin (102) includes a heatingsubsystem configured to preheat the supply of raw materials (108).Accordingly, the nano-scale electrospray deposition system (100)provides a mechanism necessary for loading and supplying raw materials(108).

In operation of the regulating system (110), an inert gas (124) is usedto provide a substantially air-free environment for the raw materials.The inert gas (124) enters the gas supply conduit (112) from a source(not shown). Examples of inert gases include, but are not limited to,nitrogen, argon, and carbon dioxide. The gas (124) flows through the gassupply conduit (112) toward the sealing device (114). A gas regulatingdevice (not shown) regulates the gas pressure within the cavity (106) toa predetermined or configurable value. When the gas pressure within thecavity (106) decreases below the predetermined or configured value, theregulating device allows or enables inert gas (124) into the cavity(106) through the gas supply conduit (112). The inert gas (124) flowsinto the cavity (120) of the gas inlet conduit (118) and into the cavity(106) of the material supply bin (102). Accordingly, the raw materials(108) are protected from extended exposure to air through a blanket ofan inert gas (124).

The nano-scale electrospray deposition system (100) also includes a rawmaterials transfer device (130) operatively coupled to the materialsupply bin (102) through the material outlet conduit (122). The rawmaterial transfer device (130) is shown herein with a casing (132) thatdefines a cavity (134) therein that contains a screw element, orflighting (136). In the embodiment illustrated in FIG. 1, the rawmaterials transfer device (130) is a screw conveyor or an auger conveyorSimilarly, in one embodiment, the raw materials transfer device (130)may be any solid material handling device that transfers solid rawmaterials including, without limitation, such as a belt conveyor, avolumetric feeder, and a gravimetric feeder. In addition, in at leastone embodiment, the raw materials transfer device (130) is adapted totransport materials in a liquid phase, and in some embodiments, withentrained solids therein. The materials transfer devices (130) for suchembodiments include, without limitation, types of screw conveyors, beltconveyors, and positive displacement pumps. The flighting (136) includesa plurality of protrusions (138) that defines a helicoid configuration.The protrusions (138) are coupled to a flighting shaft (140) that isoperatively coupled to a drive device (142) that rotates the flightingshaft (140) in the directions shown by the arrow (144). The drive device(142) is any motion device including, without limitation, a constantspeed electric motor and a variable speed drive. A pitch of the helicoidprotrusions (138) is proportional to a desired volume of the rawmaterials (108) per rotation of the flighting (136). In at least oneembodiment, the raw materials transfer device (130) includes an inertgas input and regulating system similar to the system (110). At leastsome embodiments of the nano-scale electrospray deposition system (100)include a plurality of transfer devices (130). Accordingly, nano-scaleelectrospray deposition system (100) includes the capabilities totransfer raw materials (108) within the nano-scale electrospraydeposition system (100) through one or more material transfer devices(130).

The raw materials transfer device (130) is coupled in flow communicationwith a tundish (150). As shown, the tundish (150) includes a casing(152) extending over at least one layer of insulation (154), that inturn extends over an interior liner (156). The interior liner (156)defines a molten material cavity (158) therein. The liner (156) extendsto the raw materials device (130) to form a tundish inlet conduit (160)and defines a cavity (162) therein that is coupled in flow communicationwith the flighting (136) to receive raw material (108) therefrom. Thetundish (150) includes a heating subsystem or heating element (notshown), and hereinafter referred to as the heating subsystem, that meltsthe raw material (108) into a molten state to form molten material(164). The heating subsystem includes any heating mechanisms withsufficient heat generation capacity to melt or change the state of theraw materials (108) into the molten state (164). Examples of heatingmechanisms, including, without limitation, induction heating devices andnatural gas combustion devices. The liner (156) further extends fromtundish (150) to form a tundish outlet conduit (166) and defines acavity (168) therein that is coupled in flow communication with moltenmaterial cavity (158) to receive molten material (164) therefrom. Thetundish (150) also includes an inert gas input and regulating system(170) that includes a gas supply conduit (172), a sealing device (174),and a gas inlet stub (176) that forms a gas inlet conduit (178) and acavity (180) therein, where the gas inlet conduit (178) is in flowcommunication with the gas supply conduit (172). Operation of the inertgas input and regulating system (170) is substantially similar tooperation of the inert gas input and regulating system (110) describedelsewhere herein. Accordingly, the nano-scale electrospray depositionsystem (100) includes tools to melt to the raw materials (108) andmaintain the melted raw materials in a molten state or condition forfurther use in the electrospray fabrication process, as discussedfurther herein.

The nano-scale electrospray deposition system (100) further includes anano-scale electrospray deposition apparatus (182). As shown, theapparatus (182) includes a casing (184) that defines a molten materialreservoir (186) therein. The reservoir (186) is operatively coupled inflow communication with tundish outlet conduit (166) to receive themolten material (164) therefrom and maintain the molten material (164)therein. Additional materials (not shown in FIG. 1) may be added to themolten material (164) to form one or more nano-scale compositions (188).The casing (184) includes a casing extension (190) that defines areservoir outlet capillary (192) operatively coupled in flowcommunication with the molten material reservoir (186). The nano-scaleelectrospray deposition apparatus (182) also includes an outlet nozzle(194) operatively coupled in flow communication with the reservoiroutlet capillary (192) to fabricate the nano-scale materials, e.g.,nano-particles or nano-composites (196). The apparatus (182) furtherincludes heating devices (198), shown herein as inductive heating coils,and an inert gas input and regulating system (110) and (170). Additionalstructural and operational descriptions of nano-scale electrospraydeposition apparatus (182) are discussed further herein. Accordingly,the molten materials (184) in the form of specific nano-scalecompositions (188) are electrosprayed to fabricate specificnano-particles or nano-composites (196).

In operation, the nano-scale electrospray deposition system (100)receives a supply of raw materials (108) within the cavity (106) of thematerial supply bin (102). Once the bin (102) is filled to apredetermined level with the raw materials, the bin (102) is sealed bythe inert gas input and regulating system (110) to regulate the gas(124) pressure within the cavity (106). The gas pressure may be apredetermined value or a configurable value. The predetermined andconfigured value of gas (124) pressure in the material supply bin (102)reduces ingress of air into the bin (102) and also mitigates exposure ofthe raw materials (108) to air. In one embodiment, the gas pressureranges from about 10 pounds per square inch (psi) (about 69 kiloPascal(kPa)) to about 20 psi (about 138 kPa). It is understood that some ofthe raw materials (108) may be reactive with air. In addition, the inertgas (124) pressure provides a motive force in addition to gravity totransfer the raw materials (108) from the bin (102) to the raw materialstransfer device (130) through the material outlet conduit (122).Furthermore, the gas (124) prevents formation of a vacuum lock when thematerials (108) exit the bin (102). Accordingly, nano-scale electrospraydeposition system (100) transfers raw materials (108) through one ormore material transfer devices (130).

In operation, the device (130) transfers the raw materials (108) at apredetermined and configurable rate to the tundish (150). The tundish(150) heats the raw materials (108) to a melting point of the materials(108) to produce a molten material (164) that is stored in the moltenstate within the molten material cavity (158). In one embodiment, themolten material (164) temperature ranges from about 800 degrees Celsius(° C.) (about 1472 degrees Fahrenheit (° F.)) to about 1,000° C. (1832°F.), with the temperature being dependent on the melting point of thecomposition. The inert gas input and regulating system (170) regulatesthe gas (124) pressure within the cavity (158) to a predetermined andconfigurable value to minimize exposure of the molten material (164) toair, provide a motive force in addition to gravity to transfer themolten material (164) from the tundish (150) to the nano-scaleelectrospray deposition apparatus (182) through the tundish outletconduit (166), and prevent the formation of a vacuum lock when themolten material (164) exits the tundish (150). In one embodiment, theregulating system (170) regulates the pressure of the gas (124) in arange from about 10 psi (69 kPa) to about 20 psi (138 kPa). Thenano-scale electrospray deposition apparatus (182) receives the moltenmaterial (164) within the molten material reservoir (186) and mixes thematerial (164) with other materials to produce one or more nano-scalecompositions (188) therein. The inert gas input and regulating system(110) and (170) regulates the gas (124) pressure within the reservoir(186) to a predetermined, or in one embodiment configurable, value tominimize exposure of the nano-scale compositions (188) to air, provide amotive force in addition to gravity (and electric fields, discussedfurther elsewhere herein) to fabricate the nano-scale materials, e.g.,nano-particles and nano-composites (196), with the gas (124) to preventformation of a vacuum lock when the nano-composites (196) exit the bin(102). In one embodiment, system (110) regulates the gas pressure of thegas (124) from about 10 psi (69 kPa) to about 20 psi (138 kPa).Accordingly, the raw materials (108) are melted and transferred to anano-scale electrospray deposition apparatus (182) for fabricatingnano-particles and nano-composites (196), and engineered products withtailored properties.

Construction of the Nano-Scale Electrospray Deposition Apparatus

Referring to FIG. 2, a sectional schematic view is provided illustratingone embodiment of a nano-scale electrospray deposition apparatus (200).Each of the dimensions, including height (“Y”), length (“X”), and width(or depth) (“Z”), are shown for reference, where the dimensions areorthogonal to each other in physical space. The apparatus (200) is shownwith a casing (206) that defines a molten material reservoir (208) forholding a molten material (210) therein. In one embodiment, the moltenmaterial (210) temperature ranges from 800° C. (1472° F.) to about1,000° C. (1832° F.), with the temperature being dependent on themelting point of the composition. A reservoir gas (212) occupies aportion (214) of the molten material reservoir (208) adjacent to themolten material (210). The apparatus (200) further includes an inert gasinput and regulating system (216) that includes a gas supply conduit(218) and sealing devices (220), where the system (216) is in flowcommunication with the portion (214) of the molten material reservoir(208). The inert gas input and regulating system (216) regulates a gasflow (222) through conduit (218) to regulate reservoir gas (212)pressure within the reservoir (208) to a predetermined or configurablevalue. In one embodiment, system (216) regulates the gas pressure of thereservoir gas, e.g. inert gas, (212) from about 10 psi (69 kPa) to about20 psi (138 kPa). The gas pressure (212) in the reservoir (208) reducesingress of air into the reservoir (208) thereby mitigating exposure ofthe molten material (210) to air. In one embodiment, select forms of themolten material (210) may be reactive with air, and as such mitigationof exposure to air may be warranted. In addition, the reservoir gaspressure (212) provides a motive force in addition to gravity (andelectric fields) to the transfer the molten material (210) through theapparatus (200), and prevent the formation of vacuum lock when themolten material (210 exits the apparatus (200). Accordingly, the moltenmaterial (210) is maintained under pressure and air infiltration isprevented through the pressurization of the reservoir (208) with aninert gas (212).

The nano-scale electrospray deposition apparatus (200) is shown with aplurality of induction heating coils (224) that extend around anexternal surface of the casing (206). The heating coils (224) serve toheat and induce mixing of the molten material (210) housing within thecasing (206). In one embodiment, the heating coils (224) are replacedwith an alternative heating method to provide supplementary heating tothe material (210). A non-limiting example of an alternative heatingmethod includes to, natural gas combustion. A faraday cage (226) isshown operatively coupled to the casing (206). In this illustration, thefaraday cage (226) is positioned around an external surface of thecasing (206). The faraday cage (226) functions to shield the materialwithin the casing (206) from electromagnetic radiation produced, that inone embodiment is a byproduct of the induction heating coils (224). Avented heat shield (228) is shown operatively coupled to the faradaycage (226). In this illustration, the vented heat shield (228) ispositioned around an external surface of the faraday cage (226). Thevented heat shield (228) functions to shield an environment adjacent toan external surface of the heat shield from a substantial portion of theheat produced by the induction heating coils (224). An electrospraynozzle (230) is coupled to the bottom (232) of the casing (206) of thematerial reservoir (208). A capillary tube (234) is defined in thebottom (232) of the casing (206) and extends through the electrospraynozzle (230). The capillary tube (234) is coupled in flow communicationwith the material reservoir (208). An extractor electrode (236) iscoupled to the electrospray nozzle (230), and is positioned near thebottom (238) of the electrospray nozzle (230) where the capillary tube(234) defines a capillary tube exit (240). In the illustratedembodiment, the exit is an orifice (240). In one embodiment, any otherexit configuration that enables operation of the nano-scale electrospraydeposition apparatus, e.g., apparatus 200, as described herein is usedin place of the orifice. In an embodiment where the electrospray nozzle(230) is an electrically conductive nozzle, the nozzle is coated with aninsulative coating (not shown). Similarly, in an embodiment where theelectrospray nozzle (230) is fabricated with a dielectric material, thenozzle is coated with a conductive coating (not shown). Accordingly, themolten material (210) is maintained in a molten condition in preparationfor transfer from the reservoir (208) through the capillary tube (234)toward the electrospray nozzle (230).

Referring to FIG. 3, a sectional schematic view is provided illustratinga magnified portion of a nano-scale electrospray deposition apparatus(300) taken about an area 3 (shown in FIG. 2). An extractor electrode(336) is a combination of two components, i.e., an electrode forgenerating an electric field and an inductive coil for generating amagnetic field. In one embodiment, the electrode and inductive coil areseparate elements.

The combined extractor electrode and inductive element (336) (hereonreferred to as the extractor electrode (336)) generates an electricfield to maintain the electrospray nozzle at a predetermined or definedand configured electric potential. The electric field extracts themolten material (210) in the form of a jet (310) from the electrospraynozzle (330) in the direction of the arrow (344) to form a stream ofdroplets (346) of nano-particle size and drives the droplets (346)toward the stage (342). In the illustrated embodiment, the electrospraynozzle (330) is similar to the electrospray nozzle (230) and the stage(342) is similar to the stage (242). The extractor electrode (336)generates a magnetic field to limit dispersion of the stream of droplets(346). The electrosprayed droplets (346) are charged with the samepolarity, which causes the droplets (246) to repel from one another asthey are dispersed. It is understood in the art that charged particlesmoving across magnetic field lines experience a force that is orthogonalto both the magnetic field lines and the motion of the chargedparticles. If the magnetic field is strong relative to the velocity ofthe charged particles, the charge particles tend to orbit magnetic fieldlines while moving along them. Thus, the dispersive tendencies of thestream of charged droplets (346) are countered by the magnetic field.Accordingly, the extractor electrode (336) produces the expelled streamof droplets (346) that is sufficiently focused to provide depositioncontrol and accuracy on the nano-scale level.

In the exemplary embodiment, the extractor electrode (336) has atoroidal shape with the center of the toroid penetrated by theelectrospray nozzle (330). Examples of toroidal shapes may include, butare not limited to torus or toroid shapes. In one embodiment, theextractor electrode (336) includes one or more turns of wire (not shownin FIG. 3), with the turns producing a magnetic field increasingstrength for the same amount of current. In one embodiment, the quantityof turns is proportional to the increase strength of the magnetic field.The extractor electrode (336) is shaped to provide the electric fieldand the magnetic field with characteristics useful for extracting themolten material jet (310) from the electrospray nozzle (330), drivingthe stream of droplets (346) toward the stage (342), and focusing thestream of droplets on a deposition area (348) on the stage (342). In theillustrated embodiments described herein, the droplets (346) are ejectedfrom the orifice (340) at their associated terminal velocity ofapproximately 1.0026 meters per second (m/s). In one embodiment, theterminal velocity may range from 1.00 m/s to about 1.05 m/s. In oneembodiment, any ejection velocity that enables operation of thenano-scale electrospray deposition apparatus as described herein may beused. As the charged nano-particles (not shown) within theelectrosprayed droplets (346) are directed to a target position on thedeposition area (348), the velocity of the droplets (346) are controlledvia the combined extraction electrode and inductive coil positioner(336) for a predetermined and configurable distance to provide for arelatively gentle impact of the droplets (346) on the object (378). Thisgentle impact mitigates splashing and bouncing activity of the droplets(346) with respect to the object (378), and further initiates bonding ofthe droplets (346) to the object (378). A reduced impact velocity offerscontrol of the trajectory of each droplet (346) making it possible tobuild-up complex objects, such as fabricated object (378). Accordingly,the supply of droplets (346) is channeled into a narrow stream (346) ina predetermined and configurable pattern and ejected from theelectrospray nozzle (330) at a selected rate onto a target (not shown)or a newly formed layer of the fabricated object (378) are aligned,where the alignment by a combined extractor and inductive element (336)deposits the droplets (346) at a predetermined and configurable point ofcontact.

Referring again to FIG. 2, the nano-scale electrospray depositionapparatus (200) is shown with a stage (242) that serves as the targetfor the electrosprayed stream of droplets (346). The stage (242) isconfigured for movement relative to the electrospray nozzle (230) inthree orthogonal dimensions X, Y, and Z. The stage (242) is typicallyelectrically grounded so that it forms a planar endpoint for theelectrical field. In the exemplary embodiment, the stage (242) comprisesa utility base plate (250), a cooling chuck (252), and an object holder(254). The object holder (254) is configured for holding a fabricatedobject (not shown in FIG. 2) that results from the electrospray process.The object holder includes a surface (254 _(Surface)) defining a lateralplane (254 _(Plane)). In one embodiment, the object holder (254) holds asubstrate (not shown) onto which the electrosprayed stream of droplets(346) is deposited. In other embodiments, no substrate is used and theelectrospray deposits directly onto the object holder (254). The coolingchuck (252) is positioned underneath the object holder (254) and coupledthereto. The cooling chuck (252) is configured for cooling or otherwisereducing the temperature of the object holder (254). In at least oneembodiment, the cooling chuck (252) is equipped with one or morethermoelectric cooling chips (not shown) that use direct current (DC) totransfer heat from the object holder (254) to the utility base plate(250). In one embodiment, any method of transferring heat from theobject holder (254) that enables control of the temperature of theobject holder (254) is applied to the cooling chuck (252) and/or theobject holder (254). Examples of the heat transfer method include, butare not limited to, conductive heat transfer. The utility base plate(250) is exposed to ambient air and may be cooled or subject to acooling process with natural convection or forced air flow. Wiring (256)is operatively coupled to the utility base plate (250) for powering thecooling chuck (252) and for any sensors (not shown) that may be imbeddedin the object holder (254). Extractor electrode wiring (258) provideselectrical current to the extractor electrode (236). Accordingly, thenano-scale electrospray deposition apparatus (200) includes componentsto provide for proper handling of the droplets (346) upon egress fromthe electrospray nozzle (230).

Continuing to refer to FIG. 2, the nano-scale electrospray depositionapparatus (200) has an enclosure (260) operatively coupled to theelectrospray nozzle (230) and the molten material reservoir (208). Inone embodiment, the enclosure (260) is comprised of quartz, or anothersuitable material. The enclosure (260) is shaped such that when placedin contact with the stage (242), the enclosure (260) and the stage (242)define an enclosure cavity (262) that serves as a controlled environmentfor the electrospraying process. The enclosure (260) has a frame (264)that is slidingly coupled to the outer edges (266) of the enclosure(260). The frame (264) maintains contact with the stage (242) as thestage (242) is subject to movement. This contact keeps the enclosurecavity (262) fully enclosed during electrospray object fabrication. Theutility base plate (250) has a fluid inlet (268) to inject gases (notshown) into the enclosure cavity (262). An enclosure gasket (270)positioned relative to the bottom (272) of the enclosure frame (264)improves the sealing of the enclosure cavity (262) and allows or enablesthe stage (232) to move laterally, i.e., in the X and Y dimensionswithout disturbing a sealing of the enclosure cavity (262). In oneembodiment, the enclosure gasket (270) is comprised of a felt material,although this material should not be considered limiting. For example,in one embodiment the gasket (270) may be made of one or morealternative materials that support the functionality of the gasket(270). Accordingly, the nano-scale electrospray deposition apparatus(200) includes components to provide for proper handling of the droplets(346) upon egress from the electrospray nozzle (230).

The gas inlet (268) functions as an ingress for the enclosure cavity(262) to deliver an inert gas. In one embodiment, the gas within thecavity (262) is provided at a predetermined and configurable temperatureprofile and atmospheric conditions within the cavity (262). In oneembodiment, the inert gas is argon. Similarly, in one embodiment, theinert gas may be any material or fluid that supports the desiredenvironment in enclosure cavity (262) as described herein. In at leastone embodiment, the argon gas within the enclosure cavity (262) ismaintained at a predetermined and configurable pressure of approximatelyatmospheric pressure, e.g. 14.7 pounds per square inch (psi), (101.325kiloPascal (kPa)). Similarly, in one embodiment, the argon gas ismaintained at any pressure that enables operation of the nano-scaleelectrospray deposition apparatus, such as apparatus (200), as describedherein. In one embodiment, a partial vacuum is pulled within theenclosure cavity (262), i.e., approximately 1 psi (6.9 kPa) to about 10psi (69 kPa). In the illustrated embodiment, the argon gas is injectedinto the enclosure cavity (262) at a temperature of approximately 25° C.to about 500° C. (approximately 77° F. to 932° F.). In one embodiment,the argon gas is injected into the enclosure cavity (262) at anytemperature that enables operation of the nano-scale electrospraydeposition apparatus (including, without limitation, apparatus (200)) asdescribed herein. Accordingly, an inert gas is used to maintain thedesired environment for the droplets (346) during object fabrication.

Referring again to FIG. 3, in at least one embodiment, the electrospraynozzle (330) has a valve (374) to control the flow rate of the moltenmaterial jet (310) through the nozzle (330) to form the droplets (346).In one embodiment, a method of regulating flow of the molten materialjet (310) is used including, without limitation, a pump operativelycoupled to a variable speed drive device. In a further embodiment, noregulating devices are used and flow of the molten material jet (310) iscontrolled, for example, and without limitation, by changing thepressure of the reservoir gas (212) in the upper portion (214) of themolten material reservoir (208). In a further embodiment, the flow rateof the molten material jet (310) is determined through regulation of theconcentrations of the individual constituents, as discussed further withrespect to FIG. 8. in the molten material jet (310) betweenapproximately 10⁻⁴ weight percent (wt %) to approximately 100 wt %.

The flow of the molten material jet (310) may be controlledelectrohydrodynamically. Such control of flow of the molten material jet(310) is achieved through modulation of one or more electricalcharacteristics of electric power transmitted to the extractor electrode(336). Examples of these electrical characteristics include, but are notlimited to, modulation of voltage, current, frequency, and waveform. Forexample, the controlled voltage may be within a range of approximately0.5 kilovolts (kv) to approximately 40 kv, the current may be maintainedwithin a range of approximately 0.1 microampere (pumps) to 3.0 amps, andthe frequency may be controlled from direct current (DC) with asubstantially constant frequency of 0 Hertz (Hz) to an alternatingcurrent (AC) of approximately 100 gigahertz (GHz). In one embodiment,any voltages, currents, and frequencies that enable operation of theextractor electrode (336) as described herein may be used. Also, in oneembodiment, any waveforms that enable operation of the extractorelectrode as described herein may be used, including, withoutlimitation, sine, square, and triangular waveforms. Accordingly, controlof the flow rate of the molten material jet (310) provides for controlof the size of the droplets (346), where flow control is enabled throughone or more of control of constituent concentrations in the moltenmaterial jet (310), modulation of the electrical characteristics of theextractor electrode (336), regulating the pressure in the moltenmaterial reservoir (208), and regulating a position of the valve (374),to produce a flow rate of approximately 10⁻³ nano-grams per minute(ng/min) to approximately 10⁸ ng/min.

The electrosprayed stream of droplets (346) emerges from a Taylor cone(376) that forms on the capillary tube exit port, or orifice (340) whenthe electric field draws the molten material jet (310) out of thecapillary tube (334). Dispersion of the stream of droplets (346) islimited by the magnetic field. A region on fabricated object (378) wherethe stream of droplets (346) impacts is referred to as the depositionarea (348). The fabricated object (378) includes successive depositionlayers (see FIGS. 10-14). The stage (342) is subject to lateral movementwhile the stream of droplets (346) impacts on the fabricated object(378), forming the current deposition layer over previous depositionlayers. The distance between the electrospray apparatus (300) and thefabricated object (378) is referred to as the stand-off distance (380)or distance-to-deposition. A target stand-off distance (380) isdetermined for each pass of the nozzle (330) over the fabricated object(378) to deposit each layer. As the droplets (346) are deposited on thefabricated object (378), the actual stand-off distance (380) will tendto decrease during each pass of the nozzle (330) over the fabricatedobject (378). In one embodiment, the target standoff distance (380) isapproximately 2 millimeters (mm) for each pass. It is understood in theart that the distance (380) may range from about 1.5 to about 2.5 mmbased on the composition (310) and, in one embodiment, the flow rate ofthe composition (310). Similarly, in one embodiment, the standoffdistance (380) may be any value that enables operation of the nano-scaleelectrospray deposition apparatus (200). If no action were taken, thestand-off distance (380) would decrease for every pass of the nozzle(330) over the fabricated object (378). Accordingly, the stand-offdistance (380) is maintained at or near a target stand-off distance byadjusting the vertical position of the stage (342) to facilitatedeposition of the droplets (346) on the fabricated object (378) atpredetermined and configured velocities with predetermined andconfigured temperatures.

Additional Construction Embodiments of the Nano-Scale ElectrosprayDeposition Apparatus

Referring to FIG. 4, a sectional schematic view is provided illustratinganother embodiment of a nano-scale electrospray deposition apparatus(400). As shown, the apparatus (400) include a heating device (402) forproviding thermal energy to the stream of droplets (446). In oneembodiment, the heating device (402) is used to add thermal energy tothe stream of droplets (446) when the temperature of the droplets (446)has sufficiently been reduced before impact with the fabricated object(478). In the illustrated embodiment, the fabricated object (478) issimilar to the fabricated object (378). In at least one embodiment, theheating device (402) is a radiation source that supplies thermal energyto the stream of droplets (446) with a radiation beam (404). The heatingdevice (402) emits radiation in a portion of the energy spectrum, forexample, and without limitation, the infrared portion, and the radiationbeam (404) is a coherent photon source, for example, and withoutlimitation, a laser beam. In one embodiment, the heating device (402)emits a radiation beam (404) in any other portion of the energyspectrum, for example, and without limitation, the x-ray portion. Also,in some embodiments, the radiation beam (404) includes non-coherentphotons of varying wavelengths, to which the droplets (446) appearopaque. In the illustrated embodiment, the heating device (402) ismounted outside the enclosure (460) and the radiation beam (404) passesthrough the enclosure (460), which in the illustrated embodiment is madeof quartz. In some embodiments, the heating device (402) is operativelycoupled to the utility base plate (450) of the stage (442). In theillustrated embodiment, the stage (442) is similar to the stage (342).In one embodiment, as the stage (442) moves or is moved relative to theelectrospray nozzle (430) and hence the stream of droplets (446), aimingcontrol features for the radiation beam (404) are employed to providefor illumination of the droplets (446) with the beam (404). In theillustrated embodiment, the electrospray nozzle (430) is similar to theelectrospray nozzle (330). Alternatively, the heating device (402) maybe operatively coupled to the enclosure (460) or to the electrospraynozzle (430). Accordingly, a temperature control device may be used tocontrol the temperature of the droplets (446).

The properties of the fabricated object (478) may be adversely affectedif the droplets (446) impact when the temperature of the droplets (446)decreases below an optimum temperature range. In one embodiment, theoptimum temperature range of the droplets (446) is from about 800° C. toabout 1,000° C. (1472 to 1832° F.). Control of the temperature of thedroplets (446) is used to build one or more desired nano-structures. Inone embodiment, the temperature of the molten material (410) in thereservoir (408) is maintained at approximately 1000° C., e.g. 1832° F.through thermal energy provided by the induction heating coils (424).Also, in this embodiment, the stage (442) and the fabricated object(478) are electrically grounded and their temperatures are subject tocontrol through a cooling chuck (452). The cooling chuck (452) issimilar to the cooling chuck (252). The droplets (446) are expelled fromelectrospray nozzle (430) and impinge on the stage (442). At the pointof ejection from the nozzle (430), the droplets (446) are atapproximately 1000° C., e.g. 1832° F., due to the transfer of thermalenergy from the induction heating coils (424) to the molten material(410). In this embodiment, the target temperature for the droplets (446)at the point of impact on the fabricated object (478) is approximately500° C., e.g. 932° F., which, in this embodiment, is below arecrystallization temperature for the associated formulation. As thedroplets (446) are subject to movement toward the fabricated object(478), the heating device (402) adds thermal energy to the stream ofdroplets (446) through the emission of the beam (404). In addition, theinert argon gas within the enclosure cavity (462) is maintained at atemperature of approximately 500° C., e.g. 932° F., to supportcontrolling the temperature of the droplets (446) as the droplets (446)travel through the heated argon gas from the nozzle (430) to thefabricated object (478).

The control of the temperature of the droplets (446) is controlledthroughout the sequence of droplet (446) deposition. The initialtemperature of the molten material (410) at the point of ejection fromthe nozzle (430) is controlled to a predetermined and configured value.The distance between the nozzle (430) and the fabricated object (478),i.e., the stand-off distance (380), is controlled to a configured targetvalue. The temperature of the fabricated object (478) is maintained at apredetermined and configured temperature through the cooling chuck(452). The temperature of the argon gas the droplets (446) traverse ismaintained at a predetermined or configured value as the droplets (446)traverse the stand-off distance (380). The addition of thermal energyinto the droplets (446) through the beam (404) from the heating device(402) prior to the droplets (446) impacting the object (478) facilitatesmaintaining the droplets (446) at a predetermined and configuredtemperature value. Accordingly, at least a portion of the thermodynamiccharacteristics of the object (478) fabrication process is balanced.

Referring to FIG. 5, a sectional schematic view is provided illustratingyet another embodiment of a nano-scale electrospray deposition apparatus(500). The apparatus (500) is shown with a first optical profilometer(582) that is configured to measure the distance from the first opticalprofilometer (582) to the fabricated object (578). In the illustratedembodiment, the fabricated object (578) is similar to the fabricatedobject (478). As the stage (542) is subject to movement, the firstprofilometer (582) measures the distance from the stage (542) to thefabricated object (578) at specific time intervals. Profile data aboutthe current deposited layer (not shown in FIG. 5) of the fabricatedobject (578) is created. In the illustrated embodiment, the stage (542)is similar to the stage (442). The profile data associated with thecurrent deposited layer is sent to a main control unit (584) via aprofilometer communication link (586), which may be wired or wireless.In some embodiments, a second optical profilometer (588) is employed,and in some other embodiments more than two optical profilometers areemployed.

The main control unit (584) uses collected profile data to control theelectrospray apparatus (500) during deposition of a subsequentdeposition layer. For deposition of the subsequent deposition layer, themain control unit (584) subjects the stage (542) to movement in avertical direction to maintain the stand-off distance (380) at thetarget stand-off distance, based on the profile data of the proceedingdeposition layer. The main control unit (584) also uses the profile datato compensate for any detected errors in a previous deposition layer.For example, if the profile data of the proceeding deposition layerindicates that some region of the fabricated object (578) is greaterthan desired or expected, the main control unit (584) can make acorrection on the subsequent deposition layer by modifying the flow rateof molten material (510) through the electrospray nozzle (530) when overa region of the fabricated object (578) identified with the detectederror. In the illustrated embodiment, the electrospray nozzle (530) issimilar to the electrospray nozzle (430). Likewise, if the profile dataof the proceeding deposition layer indicates that some region of thefabricated object (578) is too shallow or shallower than expected, themain control unit (584) can make a correction on the subsequentdeposition layer by modifying the flow rate of molten material (510)through the electrospray nozzle (530) when the nozzle (530) is over theassociated region of the fabricated object (578) identified with thedetected error. The main control unit (584) controls the flow rate ofthe molten material (510) through using the valve (374) or in otherways, such as changing the pressure of the reservoir gas (512) in thematerial reservoir (508) or changing the electrical conditions of theextractor electrode (536).

The main control unit (584) is connected by main control unitcommunication links (590) to one or more sub-control units operativelycoupled to the associated devices through device communications links(592). The illustrated embodiment has a first sub-control unit (594) forcontrolling the stage (542), a second sub-control unit (596) forcontrolling the extractor electrode (536), and a third sub-control unit(598) for controlling the heating device (402). Other embodiments mayhave a different quantity of sub-control units, depending on thecomponents that are to be regulated. The extractor electrode (536), thepressure in the molten material reservoir (508), the temperature of themolten material (510) through the induction heating coils (524), thecooling chuck (452) operatively coupled to the stage (542) and thefabricated object (578), the heating device (402), and the inert argongas temperature within the enclosure cavity (462) are controlled throughthe main control unit (584) to control the temperature of the droplets(346) and (446) and the fabricated object (578). Accordingly, thenano-scale electrospray deposition apparatus (500) includes a controlunit and one or more sub-control units to support fabrication of objectswith varying levels of complexity.

Referring to FIG. 6, a sectional schematic view is provided illustratingyet another embodiment of a nano-scale electrospray deposition apparatus(600). As shown, the apparatus (600) includes the molten materialreservoir (608) that contains the molten material (610). As shown, thereservoir (608) is wider than the single-nozzle embodiments shown inFIGS. 2, 4, and 5, e.g., reservoirs (208), (408), and (508), toaccommodate a greater volume of molten material (610). However, the sizeand dimensions of the reservoir (608) should not be considered limiting.The apparatus (600) includes a gas inlet conduit (618) for regulatingpressure in the reservoir (608). In one embodiment, gas inlet conduit(618) regulates the pressure of the reservoir gas, e.g. inert gas, fromabout 10 psi (69 kPa) to about 20 psi (138 kPa). In the illustratedembodiment, the apparatus (600) includes a plurality of inductionheating coils (624) that extend around an exterior surface of the moltenmaterial reservoir (608), serving to heat and maintain the moltenmaterial (610) in the liquid phase and induce mixing of the moltenmaterial (610). In some embodiments, alternative heating methods areused to provide supplementary heating including, without limitation,natural gas combustion. The increased volume of the molten material(610) over the volumes of the single-nozzle embodiments shown in FIGS.2, 4, and 5 changes the determination of the thermal energy transferfrom the heating coils (624) into the material reservoir (608). A centerregion (612) of the molten material (610) is positioned at a greaterdistance from the coils (624) than that for the smaller reservoirs 208,408, and 508. Regardless of the method of introducing thermal energyinto the molten material (610) to maintain or induce the material (610)within the predetermined temperature range, e.g. from about 800° C. toabout 1,000° C. (1472 to 1832° F.), the heat flux into the center region(612) of the molten material (610) is sufficient to maintain the centerregion (612) within the predetermined temperature range. Thepredetermined rate of heat energy input into the molten materialreservoir (608) will depend on, without limitation, the physicalcharacteristics of the particular molten materials (610) and thephysical characteristics, such as size and volume, of the reservoir(608).

The apparatus (600) includes an array of electrospray nozzles (630)coupled in flow communication with the material reservoir (608) througha manifold (632) housing an array of capillary tubes (634) and an arrayof valves (674). Each valve (674) is positioned within an associatedcapillary tube (634) and is similar to valve (374) configured to controlthe flow rate of molten material (610) through the associated nozzle(630). In the illustrated embodiment, the electrospray nozzle (630) issimilar to the electrospray nozzle (530). In at least one embodiment, analternative method of regulating flow of the molten material (610) isused including, without limitation, a pump operatively coupled to avariable speed drive device. In a further embodiment, no regulatingdevices are used and flow of the molten material (610) is controlled,for example, and without limitation, by changing the pressure of thereservoir (608). Apparatus (600) includes an extractor electrode plate(636) with a plurality of openings (638) through which an associatedelectrospray nozzle (630) at least partially extends. The extractorelectrode plate (636) is similar to the extractor electrode (336) inthat the plate (636) is shaped to provide both an electric field and amagnetic field with characteristics useful for extracting the moltenmaterial (610) from the electrospray nozzles (630), thereby driving anassociated stream of droplets (646). In one embodiment, flow of themolten material (610) is controlled through modulation of one or moreelectrical characteristics of electric power transmitted to theextractor electrode plate (636), for example, and without limitation,voltage, current, frequency, and waveform. Accordingly, in order toachieve predetermined production rates of the fabricated objects (578),multiple electrospray nozzles (630) are used to achieve thepredetermined deposition rates and to form the desired patterns with thepredetermined materials.

Referring to FIG. 7, a sectional schematic view is provided illustratinganother embodiment of a nano-scale electrospray deposition apparatus(700). The apparatus (700) is a multi-nozzle electrospray apparatussimilar to apparatus (600). The apparatus (700) includes the moltenmaterial reservoir (708) that contains a plurality of the moltenmaterials (710), or compositions (710). The molten compositions (710)include a first molten composition (712), a second molten composition(714), a third molten composition (716), a fourth molten composition(718), and a fifth molten composition (720).

In one embodiment, the molten compositions (710) are each comprised ofsubstantially different materials, that is, the five molten compositions(710) each have a different chemical composition. However, each of thecompositions (710) is chemically compatible with the other compositions.In one embodiment, the compositions (710) share some chemicalcharacteristics, for example, and without limitation, isotopes of aparticular chemical element or compound. The quantity of compositions(710) is a non-limiting value. In one embodiment, any number ofcompositions (710) is placed into the reservoir (708). As shown,compositions (710) are substantially stratified to define a plurality oflayers (710 a). The stratification allows or enables positioning of thelayers (712 a), (714 a), (716 a), (718 a), and (720 a) of thecompositions (712), (714), (716), (718), and (720), respectively, in apredetermined order and with a predetermined height (H₁-H₅,respectively) in the reservoir, thereby positioning predeterminedvolumes of each of compositions (710) into the reservoir (708). Thevolume of the first composition (712) in the capillary tubes (734) isdetermined based on the height (H_(CT)) of the capillary tubes (734). Inone embodiment, horizontal stratification, rather than the verticalstratification described above, is used. For example, the horizontalstratification may be enabled through the use of concentric chamberswithin the molten material reservoir (708).

Where strict separation of the five layers (710 a) is required, aninterface (712 b), (714 b), (716 b), and (718 b) is defined for each ofthe five layers (710 a). Specifically, a first interface (712 b) isdefined between the first (712 a) and second (714 a) layers. Similarly,a second interface (714 b) is defined between the second (714 a) andthird (716 a) layers, a third interface (716 b) is defined between thethird (716 a) and fourth (718 b) layers, and a fourth interface isdefined (718 b) between the fourth (718 a) and fifth (720 a) layers. Thecompositional mixing between the layers (710 a) at the interfaces (712b), (714 b), (716 b), and (718 b) is minimized to provide for a rapidtransition between the compositions (710) to impart the desired tailoredproperties to the fabricated objects (578). In one embodiment, somemixing of the compositions (710) at their interfaces (712 b), (714 b),(716 b), and (718 b) is engineered into the electrospray depositionprocess. For example, certain fabricated objects (578) require agraduated transition from a first composition to the subsequentcomposition. Therefore, one or more of the interfaces (712 b), (714 b),(716 b), and (718 b) are engineered to include a blended mix of the twoadjacent compositions. Accordingly, fabricating the objects (578) withtailored properties with abrupt or gradual transitions is enabled.

Grain Growth Inhibition and Pinning

At least some existing tools for creating 3D electronic nano-structuresemploy, for example, electron-beam and ion-beam decomposition ofchemical vapor precursors. These beam-writing techniques suffer from thedrawbacks of time required for serial time-consuming steps to charge thesurface as well as etching and lift-off procedures, the potential ofcontamination of precursor gases, and an inherently small number ofmaterials that can be deposited. Additional methods include inert gascondensation (IGC) and other nano-powder production methods coupled withtechniques directed toward proper material consolidation. At least oneproduction deficiency with respect to nano-powder production methods isthe grain growth induced through the heat and pressure applied duringpowder consolidation, which causes materials to lose theirnano-characteristics and creates excessive porosity within thefabricated object. Similarly, at least some existing techniques designedfor nano-scale fabrication include known methods for fabricating objectsless than 100 nm in size. Some of these methods includephotolithography, electron-beam lithography, atomic force microscopy(AFM), direct writing of liquids, (e.g., dip pen nano-lithography), andscanning tunneling microscopy (STM) writing of oxides. These fabricationmethods have limitations directed to slow speeds and a constraint totwo-dimensional (2D) structures.

Referring to FIG. 8, a diagram (800) is provided illustratingelectrosprayed droplets (802) and associated bridging monolayers (804)formed by grain growth inhibitor nano-particles (806). Also, referringto FIG. 9, a diagram (900) is provided illustrating electrosprayeddroplets (902) on a substrate (912). As molten compositions (710)transit through the electrospray nozzle(s) (730), the compositions (710)are subjected to an electrical sheer stress due to the electricpotential on the nozzle(s) (730) induced through the electric fieldgenerated by the extractor electrode plate (736). The induced sheerstress transforms a stream (not shown) of molten compositions (710) intoone or more streams of electrosprayed droplets (746). In the illustratedembodiment, the electrospray nozzle (730) is similar to the electrospraynozzle (630). As the stream of electrosprayed droplets (346,446) or theplurality of streams of electrosprayed droplets (646,746) are directedtoward the substrate (912), the droplets (802,902) travel from theelectrospray nozzle(s) (730) to the substrate (912). As the nano-sizeddroplets (802) are expelled from the electrospray nozzle (730), surfacetension of the molten material (710) induces a spherical shape to thedroplets (802). In one embodiment, the object holder (254) on the stage(542) positions a fabricated object (578) that results from theelectrospray process. Initially, the object holder (254) holds thesubstrate (912) of the fabricated object (578) onto which theelectrosprayed stream(s) of droplets (746) are deposited. In someembodiments, the substrate (912) is the object holder (254).

In the illustrated embodiment, the droplets (802,902) include one of thecompositions (712), (714), (716), (718), and (720) that each include oneor more constituents. As shown, the constituents of the compositions(710) include nano-structural materials in the form of nano-particles(808) and the grain growth inhibitor nano-particles, shown in FIG. 8 at(806) and FIG. 9 at (906). The droplets (802) and (902) also include anengineered solute (810), including one or more first engineered solutematerials (not shown). Alternatively, or in addition to the solute(810), the droplets (802) and (902) include a plurality of engineerednano-particles (812), including one or more engineered nano-particlematerials. Also, one or more binding/wetting agents (910) different fromthe solute (810) are included in the droplets (802) and (902). In someembodiments, other materials are added. As illustrated, the constituentsof the electrosprayed droplets (802) and (902) are heterogeneouslydispersed. A heterogeneous mixture of the constituents within thecompositions (710) includes the relative concentrations of theconstituents varying throughout the compositions (710), and thereforethe droplets (802) and (902). However, the constituents of the droplets(802) and (902) may also be homogeneously dispersed. A homogeneousmixture of the constituents within the compositions (710) includes therelative concentrations of the constituents substantially constantthroughout the compositions (710), and therefore the droplets (802) and(902).

As the electrosprayed droplets (802) travel, grain growth inhibitorparticles (806) overcome a surface tension induced on the droplets (802)and migrate to the surface boundaries of the droplets (802) to startforming bridging monolayers (804) that bond with neighboring droplets(802). When the droplets (902) impact on the substrate (912) and turninto a splat (908), the grain growth inhibitor particles (906) finishforming bridging monolayers (904). The bridging monolayers (904) limitgrain growth of other particles to within the splat (908), therebypreserving the nano-characteristics of the fabricated object (578).Accordingly, the dynamics of the droplets (802) and (902) as theytraverse the distance from the electrospray nozzle (730) to the targetsurface are leveraged to form the fabricated objects (578).

Nano-structural materials (808) suitable for use as a constituent in thenano-scale electrospray deposition apparatus (182), (200), (300), (400),(500), (600), and (700) described herein include metal, metal alloys,metal ceramics, (especially metal carbides, and metal nitrides),inter-metallics, ceramics, and ceramic-ceramic composites. Moreparticularly, the nano-structural materials (808) include one or more ofthe following materials: Cu, FeCu, FeCo, MoSi, MoC, NbC, NiCr, TiC,NiAl, Mo₂Si, NiCr/Cr₃C₂, Fe/TiC, Mo/TiC, WC/Co, or any of the forgoingalloys with one or more of Ti, TiC, Mn, W, B, Y, Cr, Mo, Ni, Zr, Ce, Fe,Al, Si, V, and mixtures of the foregoing metals.

The grain growth inhibitors (806) and (906) are nano-grain pinningcompounds that are used to pin the nano-grain structure throughrestricting grain growth thereof, thereby stabilizing the nano-grainstructures and boundaries formed therewith. The grain growth inhibitors(806) and (906) may be modified through being heat-treated, reacted,reduced by chemical means, carburized, or nitrided to convert orpartially convert the grain growth inhibitor (806) and (906) to inducethe desired nano-grain boundary stabilization. In one embodiment, thegrain growth inhibitors (806) and (906) are incorporated into a mixtureof nano-structural materials (808) or precursors of nano-structuralmaterials along with the binding/wetting agents (910) prior to admissioninto the material supply bin (102). In one embodiment, thenano-structural materials (808) and the grain growth inhibitors (806)and (906) are added separately to a solution with the wetting/bindingagent (910). In one embodiment, the binding/wetting agent (910) and thegrain growth inhibitors (806) and (808) are the same material, but withthe binding/wetting agent (910) in a liquid phase and the nano-grainpinning compound in a solid particulate phase. In one embodiment, thebinding/wetting agent (910), such as, but not limited to, the aluminum(Al) and titanium (W) solutes (810), are used to generate the gradientalloys, and the grain growth inhibitors (806) and (808) are differentmaterials. The aluminum (Al) and titanium (W) may be referred to asbinding/wetting agent precursors. Regardless of the mechanism fordelivery, the electrospray deposition of monodispersed nano-droplets asdescribed herein enables the uniform distribution of the grain growthpinning agents throughout the nano-structured materials.

The grain growth inhibitors suitable for use in the nano-scaleelectrospray deposition apparatus described herein are preferablychemically inert, amenable to uniform distribution onto or at the grainboundaries of the nano-structural material (808), and do not subtractsubstantially from the chemical, physical, and mechanical propertiesdesired in the nano-structures formed therefrom. Grain growth inhibitors(806) and (906) suitable for use as a constituent in the compositions(710) for use with the nano-scale electrospray deposition apparatus(182), (200), (300), (400), (500), (600), (700) described herein includemetal, metal alloys, metal ceramics, (especially metal carbides, andmetal nitrides), inter-metallics, ceramics, and ceramic-ceramiccomposites. More particularly, the grain growth inhibitors (806) and(906) are materials including: B, Si, Al, Cr, Ni, Mo, Hf, Ta, Fe, W, Zr,Ce, Ti, Mo, TiC, AlSi, TiSi, TiAl, and TiB₂, and a combination thereof.In addition, materials such as rare earth metals, silicon-basedcarbides, titanium-based carbides, aluminum-based nitrides,titanium-based nitrides, BN, metal silicides, and metal aluminides maybe used.

Table 1 provides a partial list of engineered (or tailoring) solutes(810) and the associated melting points. The aluminum and the titaniumalloys may also be used as the raw materials (108) and binding/wettingagent (910) precursors.

TABLE 1 List of Engineered Binding/ Melting Point Wetting Agents andSolutes (° C.) Aluminum 660 Titanium Nickel Copper Brazing Alloys 668Magnesium Nickel Alloys 507 Brass 905 Iron Antimony Alloy 748 NickelZinc Alloy 875 Bronze (Manganese) 865

Table 2 provides a partial list of tailoring nano-particles (812) andthe associated melting points.

TABLE 2 Nano-particle Melting Temperature (° C.) Titanium-Carbide (TiC)3160 Tungsten Carbide (WC) 2870 Boron Carbide (BC) 2763 Boron Nitride(BN) 2973 Molybdenum Carbide (MoC) 2577 Silicon Nitride (SiN) 1900Tantalum Carbide (TaC) 3880

Deposition of an electrosprayed droplet (802) and (902) follows athree-stage sequence. The first stage of the sequence is an impact stagewhich occurs within approximately 21 milliseconds (msec) after ejectionof the droplet (802) and (902) from the nozzle (730). The velocity ofthe droplets (802) and (902) is approximately 1.0026 m/s and thestandoff distance (380) is approximately 2 mm. Within the range of 0microseconds (μsec) to approximately 20 μsec upon commencement ofimpact, the droplet (802) and (902) contacts the heated substrate (912)at a temperature of approximately 500° C. (932° F.). The droplet (802)and (902) deforms from a spherical shape toward a liquid disk shapereaching a maximum spread diameter. As the droplets (802) and (902) fallfrom the electrospray nozzle (730), they rapidly cool and reach aselected viscosity and temperature to attach to the substrate (912) orfabricated object (578) while simultaneously having the grain growthinhibiting materials (806) migrate to the boundary of the droplet (802).

The second stage is a recoil stage which occurs within approximately 20μsec to approximately 45 μsec upon commencement of the impact. Thedroplet (802) and (902) begins to recoil from the liquid disk shapetoward the spherical shape. However, as the kinetic energy of thedroplets (802) and (902) dissipates at least partially due to thesurface tension of the droplets (802) and (902), an oscillation of theshape of the droplets (802) and (902) occurs until the droplets (802)and (902) attains a static, flattened shape. The oscillation of thedroplets (802) and (902) after impact and during recoil is minimized dueto the small size of the droplets (802) and (902).

The third stage is a quasi-steady solidification stage which occurs morethan approximately 45 μsec upon commencement of the impact during whichthe now immobile droplet (802) and (902) retains its flattened shape,described as a splat (908). The splat (908) shrinks as the droplet(802,902) temperature decreases, thereby inducing a mechanical stresstherein. This stress is alleviated by maintaining the substrate (912)below a known recrystallization temperature such that the splats (908)diffuse together. If the stress is not alleviated, micro-cracking of thesubstrate (912) may occur.

Some existing nano-powder production techniques for 3D fabrication ofnano-scale objects require some method of sintering. These techniquesinclude stereolithography, inert gas condensation, laser vaporization,spark erosion, electro-explosion of wires, and microwave plasmatechniques. Sintering can induce creep, warpage, and grain growth in theobjects being manufactured. Accordingly, the desirednano-characteristics of the nano-structure are lost during the sinteringprocess.

As the droplets (802) and (902) are deposited, the droplets (902) arebrought into contact with each other, thereby facilitating a significantreduction in a porosity of the associated layer on the substrate (912).The splats (908) form bonded-nano-agglomerates on the substrate (912)while maintaining their flattened shape. When exposed to theelectrospray conditions, binder precursors, e.g., the aluminum (Al) andtitanium (W) that generate the gradient alloys, within the droplets(802) and (902) form crystals e.g. (814) and (914). These crystals (814)and (914) coat the grain growth inhibitor nano-particles (806) and(906), respectively, within the droplets (902) and form connectionsbetween the nano-grains that fill gaps between adjacent nano-particles.In addition, controlling the cooling rate and charge on the droplets(802) and (902) further enables the electrosprayed depositions to fillany voids within the layers formed on the substrate (912), therebyfurther decreasing the porosity of the fabricated object (578). Notably,the charge on the solidifying splats (908) enables covalent bonding ofthe splats (908) to the neighboring depositions, i.e., the underlyingsplats (908) to form a uniform nano-structure. Therefore, a combinedcovalent-metallic-ionic type of chemical bonding created in theelectrosprayed depositions eliminates the need for post-fabricationsintering to compact the deposited materials and remove any porosities.Accordingly, the robustness of the material integrity of the fabricatedobject (578) is improved through the methods of temperature control ofthe droplets (802) and (902) for a particular composition through flowcontrol of the molten material (410) as described with respect to FIG.4. The robustness of the material integrity is also attained throughmaintenance of the temperature inside the enclosure cavity (462), andmaintaining the deposited material below the recrystallizationtemperature as described in association with FIG. 4.

Referring again to FIG. 7, the first composition (712) includes a firstnano-structural material (808) and a plurality of first grain growthinhibitor nano-particles (806) and (906) including one or more firstgrain growth inhibitors. The first composition (712) also includes afirst engineered solute (810) including one or more first engineeredsolute materials (not shown). Alternatively, or in addition to, thesolute materials, the first composition (712) includes a plurality ofsecond engineered nano-particles (812) including one or more firstengineered nano-particle materials (not shown).

The second composition (714) includes a second nano-structural material(808) and a plurality of second grain growth inhibitor nano-particles(806) and (906) including one or more second grain growth inhibitors.The second composition (714) also includes a second engineered solute(810) including one or more second engineered solute materials (notshown). Alternatively, or in addition to the solute materials, thesecond composition (714) includes a plurality of second engineeredparticles (812) including one or more second engineered nano-particlematerials (not shown).

Similarly, the third, fourth, and fifth compositions (716), (718), and(720) include third, fourth, and fifth nano-structural materials (808),respectively. The third, fourth, and fifth compositions (716), (718),and (720) also include a plurality of third, fourth, and fifth graingrowth inhibitor nano-particles (806) and (906), respectively. The graingrowth inhibitor nano-particles (806) and (906) include one or morethird, fourth, and fifth grain growth inhibitors, respectively (notshown). The third, fourth, and fifth compositions (716), (718), and(720) also include at least one of a third, fourth, and fifth engineeredsolute (810), respectively, including one or more third, fourth, andfifth engineered solute materials, respectively (not shown).Alternatively, or in addition to the solute materials, the third,fourth, and fifth compositions (716), (718), and (720) include aplurality of third, fourth, and fifth engineered nano-particles (812),respectively, including one or more third, fourth, and fifth engineerednano-particle materials, respectively (not shown).

The compositions (710) include predetermined and configurablenano-structural materials (808). As used herein, the nano-structuralmaterials (808) include materials that have a microstructure with acharacteristic length scale of which is on the order of approximately 1nm to approximately 10 nm. The nano-structural materials (808) areengineered to fabricate object structures with predetermined andconfigurable mechanical properties that include, without limitation,stiffness, strength, ductility, hardness, and toughness. Thenano-structural materials (808) are also engineered to providepredetermined and configurable physical properties that include, withoutlimitation, density, electrical conductivity, and thermal conductivity.In addition, the nano-structural materials (808) are engineered toprovide predetermined and configurable chemical properties that include,without limitation, corrosion resistance. The nano-structural materials(808) are further engineered to provide predetermined and configurablemanufacturing properties including, without limitation, formability,machinability, and ease of joining with other objects. Accordingly, thenano-structural materials (808) are selected based on their engineeredand inherent mechanical, physical, electrical, and manufacturingproperties to produce a fabricated object (578) with the desiredfunctional properties.

The compositions (710) also include predetermined and configurable graingrowth inhibitor nano-particles. In one embodiment, each of thecompositions (710) has a single species of grain growth inhibitornano-particles therein corresponding to a single species of grain growthinhibitor in nano-particle form. In one embodiment, at least one of thecompositions (710) has more than one species of grain growth inhibitornano-particles therein such that the associated compositions includemore than one species of grain growth inhibitor in nano-particle formtherein.

In addition to the nano-structural materials (808) and the grain growthinhibitors in nano-particle form, at least one or more of thecompositions (710) includes at least one of an engineered solute (810)and engineered nano-particles (812). The engineered solutes (810)include one or more engineered solute materials in an engineeredsolution such that the associated precipitates provide engineered, i.e.,tailored properties once they precipitate out of solution to assist instabilizing the nano-grain structure of the deposited layers on thefabricated objects (578). In one embodiment, a portion of theprecipitates migrate to the boundary while other portions of theprecipitates migrate throughout the nano-grain structure therebystrengthening the nano-grain structure. In one embodiment, theprecipitates are, for example, a material that has a higher meltingtemperature, e.g., see Table 2, than materials selected with a lowermelting temperature, e.g., the titanium alloy in Table 1. Theprecipitates are nano-particle-sized, i.e., that have a microstructurewith a characteristic length scale of which is on the order ofapproximately 1 nm to approximately 10 nm. In some embodiments, ratherthan, or in addition to, the engineered solutes (810) at least one ormore of the compositions (710) include engineered nano-particles (812)therein. The engineered nano-particles (812) differ from the engineeredprecipitates in that the engineered nano-particles (812) are notdissolved in a solution and are added to the associated compositions inthe form of a flowable solid with, or, in one embodiment, without, aflow enhancing liquid. See Table 1. The engineered nano-particles (812)include one or more engineered nano-particle materials therein.Accordingly, the engineered solute, (810) engineered solute materials,engineered nano-particles (812), and engineered nano-particle materialsare selected or specifically manufactured to produce tailorednano-composites (in the form of engineered nano-particles (812)) thatare then used to produce tailored nano-structures that in turn definetailored fabricated objects (578).

As used herein, the term “nano-structures” describes structures that areformed through the electrospray deposition process that have amicrostructure with a characteristic length scale of which is on theorder of approximately 1 nm to approximately 100 nm. The term “objects”as used herein describes those objects fabricated (578) through theelectrospray deposition process that have a characteristic length scalegreater than approximately 100 nm on which the nano-structures areformed. Such fabricated objects (578) include, without limitation,electrodes for nano-scale energy conversion devices, micro-devices andmicro-tools for virtually any industry, and macroscopic devices andtools that are easily discernable with the unaided eye.

In addition to defining tailored nano-composites in the form ofengineered nano-particles (812), as used herein the terms “engineered”and “tailored” indicate particular programmed, configured, orconfigurable properties and characteristics of the nano-structuresproduced through electrospray deposition of the nano-compositenano-particles produced through the electrospray deposition process. Theengineered nano-structures include at least one of configurednon-graduated properties and configured graduated properties.Non-limiting examples of configured non-graduated properties of anano-structure include uniform color and uniform strength throughout thefabricated object (578).

Non-limiting examples of configured graduated nano-structure propertiesinclude graduated strength properties, and non-uniform electrical andthermal conductivities, where the graduated properties vary as afunction of at least one physical dimension. The graduation of theproperties is one of linear and non-linear. In addition, graduatedproperties include gradient alloys, where the material composition ofthe materials deposited on a substrate (not shown) through theelectrospray process described herein varies as a function of at leastone physical dimension. The graduated properties may include variationsin a first property and a second property, where the first and secondproperties are either similar properties or different properties. In oneembodiment, the variations of the properties are created through varyingthe concentrations of the constituents of the compositions, including,without limitation, removing one or more constituents and adding one ormore constituents. Accordingly, engineered fabricated objects (578)manufactured through the electrospray deposition process describedherein include particular tailored properties and characteristics thatare either relatively uniform with respect to the three physicaldimensions or vary with respect to one or more of the three physicaldimensions.

Nano-Material (Layer) Deposition and Nano-Structure Formation

Referring to FIG. 10, a diagram (1000) is provided illustrating agradient alloy (1002) with a linear gradient (1004). Three depositionlayers (1006), (1008), and (1010) are shown, although this quantity ofdeposition layers is a non-limiting value. As shown, a first depositionlayer (1006) is overlaid with a second deposition layer (1008) that isin turn overlaid with a third deposition layer (1010). The materialcomposition of the layers (1006), (1008), and (1010) is substantiallysimilar and each layer includes one or more constituents. In oneembodiment, each layer (1006), (1008), and (1010) includes one or moredifferent compositions that are deposited sequentially for each oflayers (1006), (1008), and (1010). Each layer (1006), (1008), and (1010)extends approximately similar distances in the Y-dimension such thateach of layers (1006), (1008), and (1010) has a similar thickness. Inone embodiment, the three layers (1006), (1008), and (1010) have anydimensional values extending in three-dimensional space. A region (1012)with a higher value of a property is shown position in a region (1014)with a lower value of the property is shown in a different region fromregion (1014) where the value of the property decreases linearly alongthe X-axis in the direction of an arrow (1016). In one embodiment, thegraduated nano-structures formed include one or more gradient alloystherein, where each of the gradient alloys defines one or more speciesof the graduated nano-structures with a material composition the varieswith respect to at least one physical dimension. A non-exhaustive listof properties that may be varied includes constituent concentration,stiffness, strength, ductility, hardness, density, electricalconductivity, thermal conductivity, corrosion resistance, andmachinability. While one property is shown linearly varying in onedimension in FIG. 10, in one embodiment the property is varied inmultiple dimensions. In one embodiment, more than one property is variedin one or more dimensions. Accordingly, graduated nano-structuresincluding gradient alloys with linear gradients are formed through thedeposition of a plurality of layers as described herein.

Referring to FIG. 11, a diagram (1100) is provided illustrating agradient alloy (1102) with a non-linear gradient (1104). Threedeposition layers (1106), (1108), and (1110) are shown, although thequantity of layers is a non-limiting value. As shown, a first depositionlayer (1106) is overlaid with a second deposition layer (1108) that isin turn overlaid with a third deposition layer (1110). In addition, thematerial composition of the three layers (1106), (1108), and (1110) issubstantially similar and each layer includes one or more constituentsas described elsewhere herein. In one embodiment, each layer (1106),(1108), and (1110) includes one or more different compositions that aredeposited sequentially for each of layers (1106), (1108), and (1110). Inaddition, as shown, each layer (1106), (1108), and (1110) extendsapproximately similar distances in the Y-dimension such that each oflayers (1106), (1108), and (1110) has a similar thickness. In oneembodiment, the layers (1106), (1108), and (1110) have any dimensionalvalues extending in the three dimensions (X, Y, Z). A first region(1112) with a lower value of a property is shown in a first region(1114), e.g. to the left, with a higher value of the property is shownin another region, e.g. to the right, where the value of the propertyincreases substantially instantaneously along the X-axis at an interface(1116). In one embodiment, the graduated nano-structures formed includeone or more gradient alloys therein, where each of the gradient alloysdefines one or more species of the graduated nano-structures with amaterial composition that varies with respect to at least one physicaldimension. A non-exhaustive list of properties that may be variedincludes constituent concentration, stiffness, strength, ductility,hardness, density, electrical conductivity, thermal conductivity,corrosion resistance, and machinability. While one property is shownvarying in one dimension in FIG. 11, in one embodiment, the property isvaried in multiple dimensions. In one embodiment, more than one propertyis varied in one or more dimensions. Accordingly, graduatednano-structures including gradient alloys with non-linear gradients areformed through the deposition of a plurality of layers as describedherein.

Referring to FIG. 12, a diagram (1200) is provided illustrating alinearly-graduated conjoined deposition layer (1202). Also, referring toFIG. 7, in one embodiment, each of the compositions (710) issubstantially homogeneous within the associated layers (710 a) and eachof the substantially homogeneous compositions (710) is dissimilar toeach other. When the associated deposition layers are deposited on asubstrate (1208) through nano-scale electrospray deposition apparatus(700), the layers form a graduated conjoined deposition layer (1202),where each layer (1204) and (1206) is substantially homogeneous.Specifically, a first deposition layer (1204) is deposited on asubstrate that includes the first homogeneous composition (712) and asecond deposition layer (1206) is deposited on at least a portion of thefirst deposition layer (1204), where the second deposition layer (1206)includes the second composition (714), e.g. a homogenous composition.The overall material composition of the graduated conjoined depositionlayer (1202) varies with respect to at least one physical dimension. Onenon-limiting example includes the height (Y-dimension) of the layer(1206) above the substrate (1208) varying as a function of positionalong the length (X-dimension) of the substrate (1208), thereby formingthe graduated conjoined deposition layer (1202) with a substantiallylinear interface (1210). In one embodiment, the graduated conjoineddeposition layer (1202) may also vary in the width, e.g. the Zdimension, through proper deposition of the first homogeneouscomposition (712) and the second composition (714). In one embodiment,this process is extrapolated to all of the subsequent deposition layersdeposited by the apparatus (700) such that each layer, or partial layer,varies from the previous and subsequent layers with respect to theassigned properties. In one embodiment, the first composition (712)and/or the second composition (714) are not homogeneous, and the firstdeposition layer (1204) and/or the second deposition layer (1206)deposited therefrom are also not homogeneous. In one embodiment, thegraduated nano-structures formed include one or more of the graduatedconjoined linear deposition layers (1202) therein, where each of thegraduated deposition layers (1202) defines one or more species of thegraduated nano-structures with a material composition that varies withrespect to at least one physical dimension. Accordingly, by formingconjoined graduated deposition layers (1202), graduated nano-structureson fabricated objects (578) are formed.

Referring to FIG. 13, a diagram (1300) is provided illustrating anon-linearly-graduated conjoined deposition layer (1302). Also,referring to FIG. 7, for those embodiments where each of thesubstantially homogeneous compositions (710) is dissimilar to eachother. When the associated deposition layers are deposited on asubstrate (1308) through nano-scale electrospray deposition apparatus(700), the layers form a graduated conjoined deposition layer (1302),where each layer (1304), (1306), and (1308) is substantiallyhomogeneous. A first deposition layer (1304) is deposited on a substrate(1310) that includes the first homogeneous composition (712), a seconddeposition layer (1306) is deposited on at least a portion of the firstdeposition layer (1304), where the second deposition layer (1306)includes the homogeneous second composition (714). A third depositionlayer (1308) is deposited on at least a portion of the second depositionlayer (1306), where the third deposition layer (1308) includes thehomogeneous third composition (716). In one embodiment, the thirddeposition layer (1308) is also deposited on at least a portion of thefirst deposition layer (1304). The overall material composition of thegraduated conjoined deposition layer (1302) varies with respect to atleast one physical dimension. One non-limiting example includes theheight (Y-dimension) of the second deposition layer (1306) varying abovethe substrate (1310) as a function of position in the length(X-dimension) along the substrate (1308), thereby forming the graduatedconjoined deposition layer (1302). In one embodiment, the graduatedconjoined deposition layer (1302) may also vary in the width(Z-dimension) through proper deposition of the first homogeneouscomposition (712), the second composition (714), and the thirdcomposition (716). In one embodiment, this process is extrapolated toall of the deposition layers deposited by the apparatus (700) such thateach layer, or partial layer, varies from the previous and subsequentlayers with respect to the assigned properties. In one embodiment, thefirst composition (712) and/or the second composition (714) and/or thethird composition (716) are not homogeneous, and the first depositionlayer (1304) and/or the second deposition layer (1306) and/or the thirddeposition layer (1308) are also not homogeneous. In one embodiment, thegraduated nano-structures formed include one or more of the graduatedconjoined non-linear deposition layers (1302) therein, where each of thegraduated deposition layers (1302) defines one or more species of thegraduated nano-structures with a material composition that varies withrespect to at least one physical dimension. Accordingly, by formingconjoined graduated deposition layers (1302), graduated nano-structureson fabricated objects (578) are formed.

Referring to FIG. 14, a diagram (1400) is provided illustrating ahomogeneous conjoined deposition layer (1402). In one embodiment,referring to FIG. 7, each of the substantially homogeneous compositions(710) is dissimilar to each other. When the associated deposition layersare deposited on a substrate (1408) through nano-scale electrospraydeposition apparatus (700), the layers form a homogeneous conjoineddeposition layer (1402), where each layer (1404) and (1406) issubstantially homogeneous. A first deposition layer (1402) is depositedon a substrate (1408) that includes the first homogeneous composition(712) and a second deposition layer (1406) is deposited on at least aportion of the first deposition layer (1404), where the seconddeposition layer (1406) includes the homogeneous second composition(714). One non-limiting example includes the material composition of thetwo layers (1404) and (1406) being substantially uniform with respect tothe height (Y) above the substrate (1408), and the length (X) and width(Z) dimensions of the two layers (1404) and (1406) along the substrate(1408), thereby forming the homogeneous conjoined deposition layer(1402) with an interface (1410). As shown, the interface (1410) issubstantially parallel to the X-axis. In one embodiment, the interface(1410) is formed with any orientation that enables operation ofapparatus (700) as described herein. In one embodiment, this process isextrapolated to all of the deposition layers deposited by apparatus(700) such that each layer, or partial layer, deposited by apparatus(700) is substantially similar to the previous and subsequent layerswith respect to the assigned properties. In one embodiment, thegraduated nano-structures formed include one or more homogeneousconjoined deposition layers (1402) therein, where each of the depositionlayers (1402) defines one or more species of the graduatednano-structures with a material composition that is substantiallyconstant with respect to at least one physical dimension. Accordingly,by forming homogeneous conjoined deposition layers (1402), substantiallyhomogeneous nano-structures on fabricated objects (578) are formed.

In one embodiment, at least one of the layers (710 a) of thecompositions (710) includes a blend of one or more nano-structuralmaterials (808). In one embodiment, the blend within the associatedlayer (710 a) is one of a homogeneous blend, a heterogeneous blend, or acombination thereof. In one embodiment, the nano-structural materialnano-particles (808) may have one or more of the followingcharacteristics: insulating, conductive, and semi-conductivenano-particles, to provide for the predetermined and configuredelectrical conductivity within a portion or the entirety of fabricatedobjects (578). The homogeneous blend of a plurality of nano-structuralmaterials (808) includes the various nano-structural materials (808)substantially homogeneously dispersed throughout the associated layer(710 a). A layer deposited by the electrospray apparatus (700) includesthe various nano-structural materials (808) substantially homogeneouslydispersed throughout the deposited layer. One non-limiting method forproducing such a blend includes mixing the desired blend ofnano-structural materials (808) as raw materials (108) prior toinsertion into the material supply bin (102). For example, in oneembodiment, the blending follows the magnetic field flux lines.Accordingly, the homogenous blending of a plurality of nano-structuralmaterials (808) within one or more of the compositions (710) providesfor positioning substantially uniform layers of deposited materials onfabricated objects (578) manufactured with electrospray apparatus (700).

In one embodiment, a heterogeneous blend of a plurality ofnano-structural materials (808) includes the various nano-structuralmaterials (808) substantially heterogeneously dispersed throughout theassociated layer (710 a). A layer deposited by the electrosprayapparatus (700) includes the various nano-structural materials (808)substantially heterogeneously dispersed throughout the deposited layer.Such heterogeneous dispersal of the blend of nano-structural materials(808) provides for positioning graduated properties throughoutpredetermined portions of the associated layers deposited throughelectrospray apparatus (700). One non-limiting method for producing theheterogeneous blends of nano-structural materials (808) includes addingan agglomerating additive to a mixture of raw materials (108) prior toinsertion into the material supply bin (102). Accordingly, theheterogeneous blending of a plurality of nano-structural materials (808)within one or more of the compositions provides for positioninggraduated properties within predetermined portions of the layers ofdeposited materials on fabricated objects (578) manufactured withelectrospray apparatus (700).

In one embodiment, one or more of the layers (710 a) of the compositions(710) is formed by a plurality of sublayers (not shown), where one ormore of the sublayers includes a homogeneous blend of a plurality ofnano-structural materials (808) and one or more sublayers includes aheterogeneous blend of a plurality of nano-structural materials (808).Extrapolating the combination of heterogeneous and homogeneous blends tomore than one layer (710 a) of the compositions (710) results in aplurality of deposition layers that impart a plurality of homogeneousportions and heterogeneous portions the fabricated objects (578).Accordingly, the combination of heterogeneous and homogeneous sublayersin the molten material reservoir (708) provides for fabricating objects(578) with homogeneous properties in portions of a layer depositedthrough the electrospray apparatus (700) and heterogeneous properties inother portions of the deposited layer, thereby forming fabricated object(578) with uniform properties and graduated properties in predeterminedportions therein.

In some embodiments, as described above, the blend of a plurality ofnano-structural materials (808) within one or more of the compositions(710) enables fabrication of objects (578) with at least portionsthereof defining graduated properties. In addition, in some embodiments,the relative concentrations of the nano-structural materials (808) inthe blends are also varied to define the graduated properties. In oneembodiment, one or more of a plurality of the grain growth inhibitors, aplurality of the engineered solute materials, and a plurality ofengineered nano-particle materials are blended either in addition to, orin place of, blending the nano-structural materials (808). The blends ofthe grain growth inhibitors, the engineered solute materials, and theengineered nano-particle materials are also one of heterogeneous,homogeneous, and a combination thereof. Accordingly, the engineeredproperties of the fabricated objects (578) are further enabled throughregulating the concentrations one or more of the grain growthinhibitors, the engineered solute materials, and the engineerednano-particle materials.

Temperature control of the droplets (746) throughout the depositionprocess is given great consideration. In one embodiment, each of thecompositions (710) requires different temperature conditions.Accordingly, the apparatus and methods for controlling temperature ofthe droplets (746) as described herein are scalable and adaptable foreach of the compositions (710).

In one embodiment, in addition to the predetermined placement ofengineered nano-structural materials (808) to form tailorednano-structures on the fabricated objects (578), sacrificial materials(not shown) are included in one or more of the molten compositions(710). The one or more compositions (710) as deposited on the fabricatedobject (578) are altered to include the sacrificial material that isremoved later to further shape the fabricated objects (578). In oneembodiment, acetone is used to remove the sacrificial material.Accordingly, any three-dimensional (3D) design can be manufacturedwithout post-fabrication machining, including the design circumstancewhen one of the various material depositions needs to be subtracted tocreate unusual 3-D shapes.

Referring to FIG. 7., the nano-scale electrospray deposition apparatus(700) includes a plurality of electrospray nozzles (730) arranged in anarray within a manifold (732). As shown, the nozzles (730) are linearlyarranged. In one embodiment, the nozzle arrangement is in the directionof the X-axis. In one embodiment, the electrospray nozzles (730) arearranged in any configuration that enables the rapid fabrication aspectsas described herein, i.e., any number of nozzles (730) are arranged inany configuration with respect to the X-axis and the Z-axis. In oneembodiment, the nozzles (730) are arranged as one or more primarynozzles (shown as nozzles (730)) and a plurality of secondary nozzles(780) operatively coupled to an associated secondary manifold (782),where the object holder (754) includes the surface (754 _(Surface))defining the lateral plane (754 _(Plane)), where the plurality ofsecondary nozzles (780) are oriented within an arcuate orientationextending about the lateral plane (754 _(Plane)). Each secondary nozzle(780) directs a stream of secondary spray droplets (784) toward thesurface (754 _(Surface)). In the illustrated embodiment, one manifold(782) and three secondary nozzles (780) are shown, where the numbers ofmanifolds (782) and secondary nozzle (780) are non-limiting. In oneembodiment, the secondary nozzles (780) are oriented orthogonally withrespect to the lateral plane (754 _(Plane)). In one embodiment, thesecondary nozzles (780) are oriented non-orthogonally with respect tothe lateral plane (754 _(Plane)). In one embodiment, the secondarymanifold (782) is coupled to the manifold (732). In one embodiment, thesecondary manifold (782) is coupled to a separate material source (notshown). In one embodiment, the nozzles (730) may also be arranged in thedirection of the Y-axis. However, the restrictions as describedelsewhere herein with respect to temperature control of the electrospraydroplets (746) and the stage (242) and (442) are factors to beconsidered in the arrangement of the nozzles (730). In one embodiment,rather than a single orifice (240) and (340), the capillary tubes (734)include a coating or pattering head (not shown) with one or moreorifices (not shown) or nozzles (not shown) as depositing nozzles forproducing a very uniform film or patterns on fabricated objects (578).The patterning head is proximate the extractor electrode plate (736)with a single or a plurality of conductive capillary orifices arrangedsingularly or in two or more rows within the manifold (732). In oneembodiment, the end position, e.g. tips, of the orifices or nozzles areplaced below the lateral plane (754 _(Plane)) of the object holder(754). In one embodiment, the orifices or nozzles are positioned aboveor parallel to the lateral plane (754 _(Plane)). In one embodiment wherethe orifices or nozzles are electrically conductive, the orifice(s) ornozzle(s) is coated with an insulative coating (not shown). In oneembodiment where the orifice(s) or nozzle(s) is fabricated with adielectric material, the orifice or nozzle is coated with a conductivecoating (not shown). Accordingly, any number of, and any configurationof, the nozzles (730) and (780) that enables operation of nano-scaleelectrospray deposition apparatus (700) as described herein are used.

The deposition patterns of the streams of droplets (746) on the object(578) are controlled through the flow rate of the compositions (710)through the array of electrospray nozzles (730). The flow rate is alsocontrolled through the alignment of the nozzles (730) with respect tothe object (578) through positioning of the stage (242) and (442). Theflow rate is further controlled through alignment of the streams ofdroplets (746) through regulation of the electric and magnetic fieldsgenerated by the combined extractor/inductive plate (736). During theelectrospray process, the rate of deposition through individual nozzles(746) is controlled through modulation of the associated valves (774).In one embodiment, portions of the object (578) will receive varyingrates of material deposition thereon, thereby further enhancing deliveryof tailored properties to the object (578). Regulation of the materials'depositions on the object (578) for each of the compositions (710) issimilarly conducted. For some compositions (710), the deposition thereofon the object (578) may be selective with respect to the portion of theobject (578) that receives the droplets (746). Accordingly, depositionof the compositions (710) through modulation of the plurality of streamsof droplets (746) through the plurality of electrospray nozzles (730)and selective alignment of the stage (242) and (442) with the nozzles(730) provides for the formation of compositional gradients on theobject (578).

The nano-scale electrospray deposition apparatus (182), (200), (300),(400), (500), (600), and (700) include a main control unit (584). Themain control unit (584) is implemented in programmable hardware devicessuch as field programmable gate arrays (FPGAs), programmable logicdevices, i.e., programmable logic controllers (PLCs), and distributedprocessing systems (DCSs), or the like. The main control unit (584)includes sufficient hardware devices, including, without limitation,processor units, memory devices, and storage devices to enable thefunctionality and execute the methods as described herein. In addition,the main control unit (584) will includes sufficient software to enablethe functionality and execute the methods as described herein. Moreover,the main control unit (584) is operatively and communicatively coupledto the associated measurement and control devices through sufficientcommunications channels, either through wires and cables, or wirelessly,to enable the functionality and execute the methods as described herein.Accordingly, any combination of hardware and software that enablesoperation of the nano-scale electrospray deposition apparatus (182),(200), (300), (400), (500), (600), and (700) as described herein isused.

Referring to FIGS. 5 and 7, deposition of the layers (1006)-(1010),(1106)-(1110), (1204)-(1206), (1304)-(1308), and (1404)-(1406), hereonreferred to collectively as the deposition layers, is controlled throughthe main control unit (584) that uses profile data collected from thefirst profilometer (582) and the a second optical profilometer (588) tocontrol the electrospray apparatus (182), (200), (300), (400), (500),(600), and (700), hereon collectively referred to as the nano-scaleelectrospray deposition apparatus, during deposition of the depositionlayers. The optical profilometers (582) and (588) measure the distanceto the fabricated object (578) from the profilometers (572) and (588) atspecific time intervals to create profile data of the fabricated object(578) as the stage (542) moves the fabricated object (578) with respectto the electrospray nozzles (530) and (730). For deposition of thesubsequent deposition layer, the main control unit (584) directs thestage (542) to move vertically as necessary to maintain the measuredstand-off distance (380) at the target stand-off distance, based on theprofile data of the proceeding deposition layer. The main control unit(584) also uses the profile data to compensate for errors in theprevious deposition layers. If the profile data of the proceedingdeposition layer indicates that some region of the fabricated object(578) is too thick, the main control unit (584) can correct on asubsequent or adjacently positioned deposition layer by slowing the flowrate of molten material (510) and (710) through the electrospraynozzle(s) (530) and (730) when over the associated region of thefabricated object (578). Likewise, if the profile data of the proceedingdeposition layer indicates that some region of the fabricated object(578) is too thin, the main control unit (584) can correct for thethickness error on the subsequent or adjacently positioned depositionlayer by increasing the flow rate of molten material (510) and (710)through the electrospray nozzle(s) (530) and (730) when over theassociated region of the fabricated object (578). The main control unit(584) controls the flow rate of the molten material (510) and (710)through using the valve(s) (374) and (774), changing the pressure of thegas in the reservoir (508) and (708) or changing the electricalconditions of the extractor electrodes (536) and (736).

Referring to FIG. 7, the main control unit (584) controls thepositioning of the stage (542) to selectively align the substrate(912,1208,1310,1408) and/or the fabricated object (578) with thepredetermined nozzles of the array of electrospray nozzle (730) todeposit the compositions (710) through predetermined initiation andcessation of the streams of droplets (746). In one embodiment, the firstcomposition (712) is extracted from the molten material reservoir (708)and deposited on the fabricated object (578) in a predetermined sequenceof nozzle (730) activation and stage (542) positioning until the firstcomposition (712) is exhausted. The main control unit (584) thensequentially deposits the second, third, fourth, and fifth compositions(714), (716), (718), (720), respectively, to form one or more of thecompositional gradients, gradient alloys, and graduated nano-structuresdescribed elsewhere herein.

In one embodiment, a computer program product having program code isresident within the main control unit (584) or resident in a networkedcomputer component operatively coupled to the main control unit (584).The program code includes sufficient program instructions to deposit thedeposition layers on the substrate (912) or the fabricated object (578)such that the deposited layers create an object configuration having theone or more predetermined object configuration characteristics. In oneembodiment, fabricated objects (578) are manufactured through a computerassisted design (CAD) software program resident within the main controlunit (584) to guide the stage (542) and initiate or terminate thedeposition of selected compositions (710) to the fabricated object(578). In one embodiment, the CAD software program is resident inanother networked computer component operatively coupled to the maincontrol unit (584). Accordingly, the two-dimensional and/orthree-dimensional (3D) fabricated objects (578) are fabricated from acomputer model in which, by software, the accurate deposition of thedesired material is guided.

Referring to FIG. 1, in one embodiment, the control unit (584) regulatesthe individual constituents of the compositions (710) as the rawmaterials (108) are added and transported through the material handlingportions of the nano-scale electrospray deposition system (100). In oneembodiment, multiple material supply bins (108) and multiple rawmaterials transfer devices (130) are used to produce variations of thecompositions (710). The concentrations of the nano-structural materials(808), the grain growth inhibitor nano-particles, the engineered solutematerials, and the engineered nano-particle materials may be varied toultimately provide any desired species of the molten compositions (710).One non-limiting example includes concentrations of a plurality ofdifferent nano-structural materials (808) mixed together to producevariations of the predetermined and configured nano-structural materialsmixtures to facilitate forming variations of the predetermined andconfigurable molten compositions (710) and subsequent graduatednano-structures on the fabricated objects (578). Therefore, each ofmolten compositions (710) is a variation of a particular mixture, wherethe degree of the configurable variations is predetermined. In otherembodiments, a plurality of nano-structural materials (808) withsubstantially different properties are mixed to form unique mixtures andunique molten compositions. Similarly, grain growth inhibitornano-particles, engineered solute materials, and engineerednano-particle materials may be varied. In one embodiment, any othermaterials required to fabricate the nano-structures as described hereinmay be used and varied. In one embodiment, other aerospace materials,such as those listed in Tables 1 and 2 above, may be used and varied. Inone embodiment, other materials that facilitate further downstreammanufacturing may be used. Accordingly, the production of the moltencompositions (710) as described herein provides for producing thecompositions (710) throughout the spectrum of constituent concentrationsnecessary to produce the fabricated objects (578).

Additional Nano-Scale Electrospray Deposition Systems

Referring to FIG. 15, a sectional schematic view is providedillustrating another embodiment of a nano-scale electrospray depositionsystem (1500). As shown, three nano-scale electrospray depositionapparatus (1582 _(A)), (1582 _(B)), and (1582 _(C)) are positioned inparallel or relatively parallel. Although three electrospray depositionapparatus is shown, this quantity is for illustrative purposes andshould be considered as a non-limiting quantity. The first nano-scaleelectrospray deposition apparatus (1582 _(A)) includes a first moltenmaterial reservoir (1508 _(A)) that contains a first moltencomposition(s) (1510 _(A)). The first nano-scale electrospray depositionapparatus (1582 _(A)) also includes a first electrospray nozzle (1530_(A)) that penetrates an enclosure (1560) with a first extractorelectrode (1536 _(A)) operatively coupled to the first electrospraynozzle (1530 _(A)). The first electrospray nozzle (1530 _(A)) isgenerally oriented toward a fabricated object (1578) positioned on astage (1542).

Similarly, a second and a third nano-scale electrospray depositionapparatus (1582 _(B)) and (1582 _(C)), respectively, includes a secondand a third molten material reservoir (1508 _(B)) and (1508 _(C)),respectively) that contains a second and a third molten composition (orcomposition) (1510 _(B)) and (1510 _(C)), respectively. The second andthird nano-scale electrospray deposition apparatus (1582 _(B)) and (1582_(C)), respectively, also include a second and a third electrospraynozzle (1530 _(B)) and (1530 _(C)), respectively, that penetrate theenclosure (1560) with a second and a third extractor electrode (1536_(B)) and (1536 _(C)), respectively, operatively coupled to therespective nozzles (1530 _(B)) and (1530 _(C)), respectively. The secondand third electrospray nozzles (1530 _(B)) and (1530 _(C)) are orientedtoward the fabricated object (1578) positioned on the stage (1542).Accordingly, a fabrication system such as the nano-scale electrospraydeposition system (1500) includes a plurality of nano-scale electrospraydeposition apparatus (1582 _(A)), (1582 _(B)), and (1582 _(C)) toefficiently produce the fabricated objects (1578). In one embodiment,rather than a plurality of extractor electrodes (1536 _(A)), (1536_(B)), and (1536 _(C)), one or more extractor electrode plates similarto the extractor electrode plate (736) are used.

Each nano-scale electrospray deposition apparatus (1582 _(A)), (1582_(B)), and (1582 _(C)) performs an electrospray deposition ofmonodispersed nano-droplets (not shown in FIG. 15) as describedelsewhere herein. Each of the three molten compositions (1510 _(A)),(1510 _(B)), and (1510 _(C)) are one of substantially similar,incremental variations of a particular composition, or different. Thestage (1542) traverses through the enclosure (1560) as necessary to bepositioned under the scheduled spray nozzle (1530 _(A)), (1530 _(B)),and (1530 _(C)) such that the fabricated object (1578) receives theappropriate material composition (1510 _(A)), (1510 _(B)), and (1510_(C)), respectively, for constructing the predetermined and configurednano-structures thereon. One or more control units (584) control theoperation of the nano-scale electrospray deposition system (1500) in amanner similar to that described elsewhere herein.

In operation, nano-scale electrospray deposition system (1500) producesthe fabricated object (1578) through serially positioning the stageunder the electrospray nozzles (1530 _(A)), (1530 _(B)), and (1530_(C)), where the three material compositions (1510 _(A)), (1510 _(B)),and (1510 _(C)) are substantially similar, and the repositioning of thestage (1542) is contingent upon the exhaustion of the materialcomposition (1510 _(A)), (1510 _(B)), and (1510 _(C)), in the presentmolten material reservoir (1508 _(A)), (1508 _(B)), and (1508 _(C)). Asingle stage (1542) is shown to transport the fabricated object (1578)with the proper orientation toward the respective nozzles (1530 _(A)),(1530 _(B)), and (1530 _(C)). However, any number of stages (1542) thatenables operation of nano-scale electrospray deposition system (1500) asdescribed herein is used for those embodiments of the system (1500)arranged to mass produce multiple copies of the fabricated object (1578)substantially simultaneously and continuously. In some alternativeembodiments, the nano-scale electrospray deposition apparatus (1582_(A)), (1582 _(B)), and (1582 _(C)) are arranged such that the threeelectrospray nozzles (1530 _(A)), (1530 _(B)), and (1530 _(C)) areoriented to allow or enable simultaneous electrospraying of the samecompositions (1510 _(A)), (1510 _(B)), and (1510 _(C)) by more than oneof the nozzles (1530 _(A)), (1530 _(B)), and (1530 _(C)). Accordingly,the nano-scale electrospray deposition system (1500) is scalable to massproduce substantially similar fabricated objects (1578).

In one embodiment, in operation, the nano-scale electrospray depositionsystem (1500) is capable of producing the fabricated object (1578)through serially positioning the stage under the electrospray nozzles(1530 _(A)), (1530 _(B)), and (1530 _(C)). The three materialcompositions (1510 _(A)), (1510 _(B)), and (1510 _(C)) are different,and the repositioning of the stage (1542) is contingent upon the timedelectrospraying of the material compositions (1510 _(A)), (1510 _(B)),and (1510 _(C)) in a predetermined and configurable sequence with thescheduled positioning of the stage (1578) to produce the predeterminedand configured nano-structures on the fabricated object (1578).Similarly, those variations of a particular material composition arealso electrosprayed to produce the fabricated object (1578). In oneembodiment, the nano-scale electrospray deposition apparatus (1582_(A)), (1582 _(B)), and (1582 _(C)) are arranged such that the threeelectrospray nozzles (1530 _(A)), (1530 _(B)), and (1530 _(C)) areoriented to allow or enable simultaneous electrospraying of thedifferent compositions (1510 _(A)), (1510 _(B)), and (1510 _(C)) by morethan one of the nozzles (1530 _(A)), (1530 _(B)), and (1530 _(C)).Accordingly, the nano-scale electrospray deposition system (1500) isscalable to mass produce different fabricated objects (1578) to form oneor more of the compositional gradients, gradient alloys, and graduatednano-structures described elsewhere herein.

Referring to FIG. 16, a sectional schematic view is providedillustrating yet another embodiment of a nano-scale electrospraydeposition system (1600). One nano-scale electrospray depositionapparatus (1682) is shown, although one apparatus (1682) is anon-limiting value and in one embodiment there may be a plurality ofapparatus (1682). The nano-scale electrospray deposition apparatus(1682) is shown with a first material reservoir (1608 _(A)) thatcontains a first molten composition(s) (1610 _(A)). The materials thatcomprise the composition (1610 _(A)) in the reservoir (1608 _(A)) aremaintained in the molten state through a first plurality of inductionheating coils (1624 _(A)). Pressure in the first material reservoir(1610 _(A)) is at least partially maintained with an inert gas input andregulating system (1616 _(A)). The nano-scale electrospray depositionapparatus (1682) also includes an electrospray nozzle (1630) coupled inflow communication with a first capillary tube (1634 _(A)) thatpenetrates an enclosure (1660) with a first extractor electrode (1636_(A)) operatively coupled to the nozzle (1630). The electrospray nozzle(1630) is generally oriented toward a fabricated object (1678)positioned on a stage (1642).

The nano-scale electrospray deposition system (1600) also includes afirst additional engineered material injection system (1602) thatsupplies engineered materials toward the fabrication of the fabricatedobject (1678) that that were not added to the first molten composition(1610 _(A)). The additional engineered materials include tailoringmaterials such as, and without limitation, grain growth inhibitornano-particles (806), engineered solutes (810), and engineerednano-particles (812), and any combinations thereof. The additionalengineered materials are either mixed into one of a homogeneous mixtureor a heterogeneous mixture. In some embodiments, the additionalengineered materials are layered. The first additional engineeredmaterial injection system (1602) includes a second material reservoir(1608 _(B)) that contains first additional engineered material(s) (1610_(B)). In one embodiment, the material(s) (1610 _(B)) may include aplurality of constituents that form a composition. Pressure in thesecond material reservoir (1610 _(B)) is at least partially maintainedwith an inert gas input and regulating system (1616 _(B)). The firstinjection system (1602) also includes a second plurality of inductionheating coils (1624 _(B)). The induction heating coils (1624 _(B)) areavailable, but, may not always be necessary to maintain the additionalengineered materials (1610 _(B)) in a molten condition. The firstadditional engineered material injection system (1602) includes a secondcapillary tube (1634 _(B)) and a conduit, i.e., a second capillary tubeextension (1634 _(D)) coupled in flow communication with the firstcapillary tube (1634 _(A)). In some embodiments, the second capillarytube (1634 _(B)) and the second capillary tube extension (1634 _(D))include fourth induction heating coil(s) (1624 _(D)) (shown operativelycoupled to the second capillary tube (1634 _(B))). Also, in someembodiments, the first additional engineered material injection system(1602) includes a second extractor electrode (1636 _(B)) for those firstadditional engineered materials (1610 _(B)) that require the associatedelectric field and/or magnetic field for extraction from the materialreservoir (1608 _(B)) and further transport to the first capillary tube(1634 _(A)).

The nano-scale electrospray deposition system (1600) also includes asecond additional engineered material injection system (1604) thatsupplies engineered materials toward the fabrication of the fabricatedobject (1678) that were not added to the first molten composition (1610^(A)). The inclusion of two injections systems (1602) and (1604) isnon-limiting. The second additional engineered material injection system(1604) includes a third material reservoir (1608 _(C)) that containssecond additional engineered materials (1610 _(C)). In one embodiment,the materials (1610 _(C)) may include a plurality of constituents thatform a composition. Pressure in the third material reservoir (1610 _(C))is at least partially maintained with an inert gas input and regulatingsystem (1616 _(C)). The second injection system (1604) also includes athird plurality of induction heating coils (1624 _(C)). The inductionheating coils (1624 _(C)) are available, but may not always be necessaryto maintain the additional engineered materials (1610 _(C)) in a moltencondition. The second additional engineered material injection system(1604) includes a third capillary tube (1634 _(C)) and a conduit, i.e.,a third capillary tube extension (1634 _(E)) coupled in flowcommunication with the first capillary tube (1634 _(A)). In oneembodiment, the third capillary tube (1634 _(C)) and the third capillarytube extension (1634 _(E)) include fifth induction heating coils (1624_(E)) (shown operatively coupled to the third capillary tube (1634_(C))). Also, in one embodiment, the second additional engineeredmaterial supply apparatus (1604) includes a third extractor electrode(1636C) for those first additional engineered materials (1610 _(C)) thatrequire the associated electric field and/or magnetic field forextraction from the material reservoir (1608 _(C)) and further transportto the first capillary tube (1634 _(A)). Accordingly, the nano-scaleelectrospray deposition system (1600) includes first and secondadditional engineered material injection systems (1602) and (1604),respectively to supplement the materials of the nano-scale electrospraydeposition apparatus (1682) to produce the engineered (tailored)fabricated objects (1678).

In operation, control of the first and second additional engineeredmaterial injection systems (1602) and (1604), respectively, includesdevices such as, and without limitation, main control unit (584)operatively coupled to field devices such as, and without limitation,regulating valves (374), second and third extractor electrodes (1636_(B)) and (1636 _(C)), respectively, and inert gas input and regulatingsystems (1616 _(B)) and (1616 _(C)), respectively. Some circumstancesfor producing the fabricated object (1678) that require additionalengineering materials (1610 _(B)) and/or (1610 _(C)) include, withoutlimitation, chemical or other physical requirements for nano-materialsthat are not in a molten state to be added to the molten materials (1610_(A)) in the first capillary tube (1624 _(A)) and temperature control ofthe molten materials (1610 _(A)) in the first capillary tube (1624_(A)). Flows of the additional engineering materials (1610 _(B)) and(1610 _(C)) are regulated through the second and/or third capillary tube(1634 _(B)) and the associated second and third capillary tubeextensions (1634 _(D)) and (1634 _(E)), respectively, into the firstcapillary tube (1634 _(A)). In some embodiments, the combination of themolten compositions (1610 _(A)) and the first additional engineeredmaterials (1610 _(B)) and/or the second additional engineered materials(1610 _(C)) produces the composition (or compositions) (not shown) thatis/are used to form the deposition layers as described elsewhere herein.In those embodiments where the additional engineered materials arelayered, the compositions of the materials being ejected through theelectrospray nozzle (1630) will change from a first composition to asecond composition as the layers are exhausted. In one embodiment, thefirst and second additional engineered material injection systems (1602)and (1604), respectively, are used with the nano-scale electrospraymulti-nozzle deposition apparatus (700). Accordingly, the first andsecond additional engineered material injection systems (1602) and(1604), respectively, provide for an alternative method of tailoring thefabricated objects (1678) with engineered nano-structures to form one ormore of the compositional gradients, gradient alloys, and graduatednano-structures described elsewhere herein.

Referring to FIG. 17, a flow chart (1700) is provided illustrating aprocess for fabricating an object with nano-structures thereon. As shownand described in FIG. 17, at least one reservoir (208), (708), (1508_(A)), (1508 _(B)), and (1508 _(C)) is provided (1702) to hold at leastone composition (210), (710), (1510 _(A)), (1510 _(B)), (1510 _(C)),respectively. In some embodiments, a plurality of reservoirs (1508_(A)), (1508 _(B)), and (1508 _(C)) are provided to hold either similarcompositions or different compositions to enable deposition of thecompositions (210), (710), (1510 _(A)), (1510 _(B)), (1510 _(C)) withincreased efficiency over that of a single-nozzle apparatus, e.g.,apparatus 200, 400, and 500 (shown in FIGS. 2, 4, and 5, respectively).A first composition (712) and (1510 _(A)) is produced (1704) throughcombining a first nano-structural material (808), a plurality of firstgrain growth inhibitor nano-particles (806) including one or more firstgrain growth inhibitors (not shown). The first composition (712) and(1510 _(A)) also includes at least one of a first engineered solute(810) including one or more first engineered solute materials (notshown), and a plurality of first engineered nano-particles (812)including one or more first engineered nano-particle materials (notshown).

A second composition (714) and (1510 _(B)) is produced (1706) throughcombining a second nano-structural material (808), a plurality of secondgrain growth inhibitor nano-particles (806) including one or more secondgrain growth inhibitors (not shown). The second composition (714) and(1510 _(B)) also includes at least one of a second engineered solute(810) including one or more second engineered solute material (notshown), and a plurality of second engineered particles (812) comprisingone or more second engineered nano-particle materials (not shown). Thefirst and second compositions (712) and (1510 _(A)) and (714) and (1510_(B)), respectively, are channeled (1708) through one or moreelectrospray nozzles (230), (730), (1530 _(A)), (1530 _(B)), and (1530_(C)) operatively coupled to the at least one reservoir (208), (708),(1508 _(A)), (1508 _(B)), and (1508 _(C)). A stage (242) and (1542) ispositioned (1710) proximate to the nozzles (230), (730), (1530 _(A)),(1530 _(B)), and (1530 _(C)), where the stage (242) and (1542) isadapted to move relative to the nozzles (230), (730), (1530 _(A)), (1530_(B)), and (1530 _(C)). The stage (242) and (1542) includes a substrateholder (254) adapted to hold a substrate (912). A surface profiledetermination device (582) and (588) is positioned (1712) proximate tothe stage (242) and (1542), where the device (582) and (588) obtains(1714) profile data of the substrate (912). A control unit (584)operatively coupled to the device (582) and (588) and the stage (242)and (1542) regulates (1716) manufacture of a pinned nano-structure (900)forming (1718) a first deposition layer (1006) with the firstcomposition (712) proximal to the substrate (912), and forming (1720) asecond deposition layer (1008) with the second composition (714)proximal to the substrate (912).

As described herein, the present disclosure is directed generally toapparatus and methods of forming nano-structures with tailoredproperties on objects while fabricating the objects. Specificcompositions are mixed to produce specific features and properties onthe fabricated objects. The compositions include one or morenano-structural materials (in the form of nano-particles) to produce thefundamental structural properties of the nano-structures that are formedas described herein. Grain growth inhibitor nano-particles are includedin the compositions to restrict growth of the grain boundaries of thematerials through pinning as they are deposited on the substrate of amaterial. In addition, the compositions also include an engineeredsolute and/or engineered nano-particles and one or more binding/wettingagents.

The compositions are electrosprayed as a plurality of moltennano-droplets where the composition, size, temperature, uniformity, rateof deposition, and precision of deposition of the nano-droplets iscontrolled. In addition, the sequence of depositing the different layersof nano-droplets is controlled. The electrospray production of moltendroplets of a controllable composition and selectable temperature enablean almost voidless final product to be fabricated with desiredproperties. The tailoring of properties enables the direct printing ofgradient alloys, where embedded work-hardening effects are an intrinsicresult of the process, and predetermined hardness values are attributedto the nano-grain composition. Current compositions of existing alloys,such as aluminum 6061 T6, can have improved properties simply byfabrication through the electrospray processes disclosed herein. Thedirect printing of the nano-structured materials provides forfabricating new materials that cannot be formed by natural processes dueto the lack of process parameter control and the lack of the uniqueconstituents needed to obtain the desired properties in the finalcomposition.

The nano-scale electrospray deposition systems and apparatus describedherein facilitate creating a combined covalent-metallic-ionic type ofchemical bonds in the electrosprayed depositions, thereby eliminatingthe need for sintering. The apparatus as described herein provides forthe direct and precise formation of a free-form two-dimensional andthree-dimensional (3D) article without the need for a mold of thearticle. In addition, the apparatus described herein provides a meansfor the constant variation of the compositions within the moltenmaterials. Pinning the grain boundaries and varying the compositions ofthe deposited layers allows or enables creating unique, tailoredproperties of the nano-structures to form one or more of thecompositional gradients, gradient alloys, and graduated nano-structuresdescribed elsewhere herein. The nano-scale electrospray depositionsystems and apparatus described herein are scalable to provide forproducing individual objects with predetermined and configurableproperties for unique and specialized service and to mass producenano-scale-sized devices for general commercial consumption.

Aspects of the present embodiments are described herein with referenceto one or more of flowchart illustrations and/or block diagrams ofmethods and apparatus (systems) according to the embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the embodiments.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present embodiments has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the embodiments in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the embodiments. Theembodiments were chosen and described in order to best explain theprinciples of the embodiments and the practical application, and toenable others of ordinary skill in the art to understand the embodimentsfor various embodiments with various modifications as are suited to theparticular use contemplated. The implementation of the nano-scalefabrication systems and apparatus described herein facilitatesfabrication of objects across a wide spectrum of uses. Accordingly, thenano-scale fabrication systems and apparatus and the associatedembodiments as shown and described in FIGS. 1-17, provide for creatingunique, tailored properties of the nano-structures to form one or moreof the compositional gradients, gradient alloys, and graduatednano-structures.

It will be appreciated that, although specific embodiments have beendescribed herein for purposes of illustration, various modifications maybe made without departing from the spirit and scope of the embodiments.In particular, the nano-scale fabrication systems and apparatus areshown as configured to produce unique two-dimensional andthree-dimensional (3D) objects on a nano-scale frame of reference.Alternatively, the nano-scale fabrication systems and apparatus may beconfigured to produce product along the size spectrum from nano-scale,such as electrodes for nano-scale energy conversion devices,micro-devices and micro-tools for virtually any industry, through themacroscopic scale that includes devices and tools that are easilydiscernable with the unaided eye. Accordingly, the scope of protectionof the embodiment(s) is limited only by the following claims and theirequivalents.

1. A method comprising: providing a first composition, the firstcomposition including: a first nano-structural material; a plurality offirst grain growth inhibitor nano-particles including one or more firstgrain growth inhibitors; and at least one of: a first tailoring soluteincluding one or more first tailoring solute materials; and/or aplurality of first tailoring nano-particles including one or more firsttailoring nano-particle materials; and providing a second composition,the second composition including: a second nano-structural material; aplurality of second grain growth inhibitor nano-particles including oneor more second grain growth inhibitors; and at least one of: a secondtailoring solute including one or more second tailoring solutematerials; and/or a plurality of second tailoring particles includingone or more second tailoring nano-particle materials; and manufacturinga pinned nano-structure with one or more tailored gradient propertiescomprising: forming a first deposition layer with the first composition,the first layer positioned proximal to an object holder; and forming asecond deposition layer with the second composition positioned proximalto the object holder.
 2. The method of claim 1, further comprisingfabricating the pinned nano-structure to include a graduatednano-structure, wherein the graduated nano-structure comprises the firstdeposition layer, the second deposition layer, or a combination thereof.3. The method of claim 2, wherein fabricating the graduatednano-structure comprises fabricating one or more gradient alloys,wherein the one or more gradient alloys includes a material compositionthat varies with respect to at least one physical dimension.
 4. Themethod of claim 3, wherein fabricating the graduated nano-structurefurther comprises: modulating one or more of a concentration of thefirst nano-structural material, a concentration of the first graingrowth inhibitor nano-particles, a concentration of the first tailoringsolute materials, and/or a concentration of the first tailoringnano-particle materials.
 5. The method of claim 4, wherein fabricatingthe graduated nano-structure further comprises: forming the firstnano-structural material comprising mixing at least a thirdnano-structural material and a fourth nano-structural material, whereinthe third nano-structural material is different from the fourthnano-structural material; and modulating concentrations of the third andfourth nano-structural materials.
 6. The method of claim 5, whereinfabricating the graduated nano-structure further comprises: modulatingone or more of a concentration of the second nano-structural material, aconcentration of the second grain growth inhibitor nano-particles, aconcentration of the second tailoring solute materials, and/or aconcentration of the second tailoring nano-particle materials.
 7. Themethod of claim 6, wherein: the second nano-structural material includesat least fifth and sixth nano-structural materials, wherein the fifthnano-structural material is different from the sixth nano-structuralmaterial; and fabricating the graduated nano-structure further comprisesmodulating concentrations of the fifth and sixth nano-structuralmaterials.
 8. The method of claim 1, further comprising forming ahomogeneous conjoined deposition layer with the first and seconddeposition layers, wherein the first composition is homogeneous and thesecond composition is homogeneous.
 9. The method of claim 1, furthercomprising forming a graduated conjoined deposition layer with the firstand second deposition layers, wherein the first composition ishomogeneous and the second composition is homogeneous.
 10. The method ofclaim 1, further comprising: generating, proximate at least one nozzle,an electric field and/or a magnetic field; extracting the firstcomposition through the at least one nozzle and directing the firstcomposition toward the object holder through the electric field and/orthe magnetic field, thereby forming first mono-dispersed droplets andforming the first deposition layer; and extracting the secondcomposition through the at least one nozzle and directing the secondcomposition toward the an object holder through the electric fieldand/or the electric field, thereby forming second mono-disperseddroplets and forming the second deposition layer.
 11. The method ofclaim 10, further comprising configuring the electric field to drive thefirst and second mono-dispersed droplets toward the object holder. 12.The method of claim 10, further comprising configuring the magneticfield to limit dispersion of the first and second mono-disperseddroplets from the at least one nozzle toward the object holder.
 13. Themethod of claim 10, further comprising regulating movement of the objectholder with respect to the at least one nozzle to maintain a targetstand-off distance between the at least one nozzle and the first andsecond deposition layers on the object holder.
 14. The method of claim13, further comprising calculating the target stand-off distance basedon profile data of the first and second deposition layers.
 15. Themethod of claim 10, wherein the at least one nozzle comprises a firstnozzle and a second nozzle, and wherein the method further comprises:storing the first composition in a first reservoir adaptively coupled tothe first nozzle; and storing the second composition in a secondreservoir adaptively coupled to the second nozzle.
 16. The method ofclaim 15, further comprising: selectively aligning the object holderwith the first nozzle; depositing the first composition on the objectholder responsive to the selective alignment; selectively aligning theobject holder with the second nozzle; and depositing the secondcomposition on the object holder responsive to the selective alignment.17. The method of claim 16, wherein depositing the first and secondcompositions comprises creating a compositional gradient.
 18. The methodof claim 10, further comprising: controlling movement of the stage, themovement to align the object holder with the at least one nozzle;extracting the first composition through the at least one nozzle untilthe first composition is exhausted from a reservoir; and sequentiallyextracting the second composition through the at least one nozzle anddelivering the second composition to the object holder, thereby forminga compositional gradient through the sequential extraction.
 19. Themethod of claim 10, further comprising: storing the firstnano-structural material in a reservoir; and coupling an injectionsystem to a conduit extending between the reservoir and the at least onenozzle.
 20. The method of claim 19, further comprising forming the firstcomposition comprising: regulating a first injection of the first graingrowth inhibitor nano-particles and the at least one of the firsttailoring solute and/or the first tailoring nano-particles into thefirst nano-structural material.
 21. The method of claim 19, furthercomprising forming the second composition comprising: storing the secondnano-structural material in the reservoir, wherein the firstnano-structural material and the second nano-structural material arelayered in the reservoir.
 22. The method of claim 10, furthercomprising: generating the mono-dispersed droplets having asubstantially uniform nano-particle size through modulating at least oneelectrical characteristic transmitted to form the electric field and/orthe magnetic field, the electrical characteristic comprising voltage,current, frequency, and/or waveform.
 23. The method of claim 10, furthercomprising the modulating a composition of the mono-dispersed dropletscomprising generating the mono-dispersed droplets.
 24. The method ofclaim 10, further comprising: maintaining the at least one nozzle at apredetermined electrical potential; emitting a jet of the at least onecomposition through an exit port of the at least one nozzle;transforming at least one material into a stream of droplets comprisingsubjecting the jet to an electrical sheer stress, wherein each droplethas an electrical charge; and controlling a size of each dropletthrough: modulating an electrical characteristic of electric powertransmitted to the extractor electrode, the electrical characteristicsele comprising voltage, current, frequency, and/or waveform; and/ormodulating a flow rate of the stream of droplets and a composition ofthe stream of droplets.
 25. The method of claim 1, wherein providing afirst composition further comprises: adding a first binding agent to thefirst composition.
 26. The method of claim 1, wherein providing a secondcomposition further comprises: adding a second binding agent to thesecond composition.
 27. The method of claim 1, further comprising:forming the first nano-structural material comprising mixing a pluralityof first nano-structural material nano-particles; and forming the secondnano-structural material comprising mixing a plurality of secondnano-structural material nano-particles, the first and secondnano-structural material nano-particles.
 28. The method of claim 1,wherein depositing first and second deposition layers on the objectholder comprises: creating an object configuration having one or moreobject configuration characteristics.
 29. The method of claim 1, furthercomprising: coupling a manifold operatively coupled to the at least onenozzle; operatively coupling a plurality of secondary nozzles to themanifold; and orienting the plurality of secondary nozzles with anarcuate orientation extending about a lateral plane defined by a surfaceof the object holder.
 30. The method of claim 29, further comprising:fabricating each secondary nozzle from a conductive material; and atleast partially coating the conductive material with an insulatingmaterial.
 31. The method of claim 29, further comprising: fabricatingeach secondary nozzle from a dielectric material; and at least partiallycoating the dielectric material with a conductive material.
 32. Themethod of claim 1, wherein: forming the first nano-structural materialcomprises blending two or more first nano-structural materials; andforming the second nano-structural material comprises blending two ormore second nano-structural materials.
 33. The method of claim 1,wherein: forming the plurality of first grain growth inhibitornano-particles comprises blending two or more of the first grain growthinhibitors; and forming the plurality of second grain growth inhibitornano-particles comprises blending two or more of the second grain growthinhibitors.
 34. The method of claim 1, wherein: at least partiallytailoring the first deposition layer with the one or more first tailoredproperties through the one or more first tailoring solute materials; andat least partially tailoring the second deposition layer with the one ormore second tailored properties through the one or more second tailoringsolute materials.
 35. The method of claim 34, wherein: at leastpartially tailoring the first deposition layer with the one or morefirst tailored properties through the one or more first tailoringnano-particle materials; and at least partially tailoring the seconddeposition layer with the one or more second tailored properties throughthe one or more second tailoring nano-particle materials.
 36. The methodof claim 35, further comprising: determining one or more tailoredgradient properties of one or more of the first and second depositionlayers.
 37. The method of claim 10, further comprising: fabricating theat least one nozzle from a conductive material; and at least partiallycoating the conductive material with an insulating material.
 38. Themethod of claim 10, further comprising: fabricating the at least onenozzle from a dielectric material; and at least partially coating thedielectric material with a conductive material.